Last year I bought a used gamecube game at GameStop in the mall. I opened it when I sat down to lunch with my fiancee there was a 20 pound note stuck inside.
I brought it to the bank and had it exchanged to US dollars, which made it almost 40 bucks at the time. The game cost me about 7 dollars, so I definitely profited on that one.
Some poor kid lost his cool british money though. My fiancee confessed that he used to hide his cash in game cases as a kid, but it’s defintely weird.
A friend and I found £400 in cash in an envelope on the ground at the Glastonbury Festival. It was seconds away from being trodding into the six-inch deep mud for good. I said we should keep it, my friend said we should hand it in. We handed it in. From the look in the lost-property dude’s eyes, it went no further than his pocket 
I haven’t lost more than a few dollars at a time, I’m usually pretty careful with my cash.
I once found a wallet containing probably $200 or more, outside of a restaurant. Fortunately for the wallet’s owner, her ID was still in there. Turns out she worked in the restaurant, and dropped her wallet leaving work. All her tips from the night were in there.
I don’t usually lose money, or at least not enough to be noticed. Probably change and the odd fiver. (Though one time I thought I was losing my mind because after nights out I’d come up short by $20-40 and thought I’d spent it or lost it without realizing while drunk… turned out my b/f was stealing from my wallet.)
As for finding, the most I’ve found is 20, or the odd wallet with credit cards which I always turned in.
I picked up two one hundred dollar bills in a grocery store a few years back. I had been downsized, my unemployment had run out, and things were pretty bleak. So I just kept it. I still feel guilty that I didn’t at least try to find the owner.
I don’t remember ever losing any significant amount of money, although I’ve come up short a few bucks several times.
I was working in a computer game store back in 1993 and was in on my day off to collect my paycheck. A friend of mine was working that evening. He was just finishing a sale for 2 guys so I waited for them to finish so I could talk to him. The guys left, so I walked up to the counter to talk with my friend, when I noticed a bank envelope on the counter. I picked it up and briefly looked inside… it had some cash in it. I looked at the opening of the store and the 2 guys who were just there, were still in front of the store, so I said to them, “Hey, does this envelope belong to either of you?” They said, “Yes” and came back in and the one guy then pulled out $10.00 and gave it to me. When I refused it he said, “You don’t understand. This has my house payment in it.” I found out that the envelope contained over $2,000.
I used to be a bartender at a casino.The bar was lined with slot machines and a lady hit a jackpot of $2500,I cashed her out and she gave me $50 as a tip,I said congrats, thanks and all that jazz then walked away to serve other guests. When I came back to that spot, there was an additional $500 on the bar.I didn’t think it was meant as a tip,since she had already given me the $50,so I called the boss over and explained what had happened since casinos are very strict about employees finding money.
(This all occurred BTW on the very day my rent was due,and had arrived at work needing to make at least $270 to cover my rent,with a half hour left I was at $202, so I was sweating the rent.)
Anyhow, the boss and I talked it over,she called her boss over and it was decided that I should turn in the loot and if it wasn’t claimed in ten days I would be allowed to claim the cash,(Which, of course, left me short of rent.)so thats what I did.
In the meantime,two other guests hit minor jackpots of a few hundred bucks and tossed me a 50 and a 20, when I tallied the days tips I was at $272,PHEW!
In the end, no one claimed the money so I was able to claim it myself on Dec.23, just in time for Xmas.
Two stories:
I gathered the money together and gave it to her. She thanked me graciously. But she looked so lost, I couldn’t just leave her there - so I asked for a contact, went to a phone booth (this was the olden days), and called her daughter, who came and collected her.
I suppose we ought to have turned it in, but how? Plus, I wasn’t going to argue with some stranger about it in the middle of the night.
I don’t remember ever finding much money (tho’ I was in a grocery store line and the guy behind me looked down and found $100 bill, dang it.) but I did lose $200 in a parking lot once. I was on my way out of town for Christmas and stopped to buy a last minute gift. Didn’t realize I had lost it (must of just slipped out, I had a kinda cheesy wallet/purse combo that wasn’t all that secure) until I was hundreds of miles away. That was a huge amount for me at the time and wasn’t an easy loss. The store was in a kinda dodgy neighborhood and I always hoped some poor person found it and got a great Christmas treat (I imagine a maudlin scene of a poor single mom finally being able to afford Christmas presents) rather than some bum blowing it on Thunderbird…
Does losing “potential” money count?
When I got a new job after college, I received stock options as part of the hiring package. Since then, there was a stock split, and an acquisition (conveting the stock in the original company into ones for the new one), leaving things at around 250 shares with a strike price (what I’d pay to exercise them) of just over $13.
Of course, once the options vested, the stock was trading at around $11-$12. Since I didn’t really feel like losing money on this “benefit”, I left the options where they were and went on with my life.
A couple of years later, the company was doing better on the market, with shares trading around $18-19. I remembered that I had options sitting there (after not thinking of them for a while), and decided that now was as good a time as any to profit from them, since I was getting ready to close on a house, and an extra grand would come in handy. I went through the broker’s web site, and had to jump through a few hoops to get my account activated (the new company transfered option management to another brokerage). Once that was done and I looked at the account information, I saw a worrying piece of data:
The options expired that day. Once fully vested, the options were only valid for another two years, and I happened to pick the expiration date to check into things.
It was already late in the day, getting close to the close of the market. I called up the phone number for trading and explained that I’d really like to profit from the options. The broker I talked to said that due to the timing of things, the only way to exercise the options would be in overnight trading, which may or may not be available.
It ended up being not possible. So I was literally a day late and ~1500 dollars short.
I once found two $20 bills folded together in a parking lot. It was in mid-December and I found it during lunchtime in a really busy shopping center. I looked around no one was anywhere near me. I couldn’t shake the feeling that this money was going to be used to buy some kid his or her only Christmas presents, so I shoved it into a Salvation Army collection thingie.
My freshman year of high school, I was having a really bad morning. I missed the bus because I got mascara in my eye (ow!) and my parents had already left for work. I ran down the street and caught my best friend’s mom leaving for work. She was really cool; I practically lived at their house back then. She took me to school. I was running down the hall to make it to my locker and first hour so I wouldn’t be late for class. Found $10 in the deserted halllway.
And once I tried to take $20 out of an ATM, and the money got kinda stuck. An extra $20 came out. It was like 9pm and no one else was around so I just kept it.
I’ve never found any money really besides the $10. I found a lady’s checkbook and stuff and returned it. Found a lady’s nice day planner and all her stuff like that in the bathroom at school this year. Left it in lost and found downstairs because I didn’t have my phone on me and couldn’t call her - asked the guy at the desk to. Hope he did.
I have a “friend” who picked up an umbrella at an empty bus stop one sunny morning. When my “friend” opened up the umbrella two weeks later, out fell a wad of cash and a bag of white powder.
My “friend” kept the cash and flushed the powder.
When I was six or so, I found around $50 on the ground near a bench in a public park.