I would never keep money that I wasn’t entitled to. I would immediately lose far more than the value of the money. Even money gained by luck as this would be requires me to waste some. If I found a bag of money in the street I’d report it. After waiting the necessary time and it remained unclaimed I could then begin to use it as I described above.
Here’s a documentary on the potential downsides of that approach:
I did find a wallet in a city park in San Francisco a few years ago. It had a DL, credit cards, random crap, and zero cash. Whether it had been accidentally dropped by the owner and pilfered later by somebody else or was dropped by a mugger or pickpocket after he pocketed the cash I couldn't say. Anyhow, it proved challenging to turn it into the PD; I had to find a substation that I could get to via bus in an unfamiliar city while also not wasting too much time as I had to go to work later that afternoon.
The policeman at the station looked at it, asked me where I found it, didn’t ask me for my personal info, shrugged, and said they’d take care of notifying the owner.
I would put most of it into savings but use some of it for home improvements. My wife wants to completely reconfigure and modernize our kitchen, and she’s willing to do a lot of the work, but it will still cost $20-$30 k, which is money we don’t currently have.
I’m retired, no pension, and I work a few days a week to help cover expenses. My wife works full time, but doesn’t get paid much, so we live off my social security and her meager paycheck. We won’t get an inheritance, so the only way I would come into “found money” is to win the lottery, which isn’t very likely.
Like a lot of posters, my first thought on “found” money was “give it back.” (I did find a diamond ring once, and promptly took it to the police station.)
As I’m not in debt and have decent savings, some combo of #3 (an expensive treat of some sort) and #5 (donate to a worthy cause).
The worthy cause would come first - a hefty donation to a non-profit that I know for sure is efficient at providing help to people in desperate straits.
The treat would probably be an upgrade on something we’ll do anyway - the kitchen needs some renovations and we’d like our next car to be electric, but we could go a little higher on the luxury scale than we most likely will (I tend to be happily frugal most of the time).
I recently came into a tidy sum of $$$$$, my share of an inheritance.
Immediately I paid down debt. Not the mortgage as there’s only 4 years remaining but I zeroed out one credit card balance that I had been bouncing around for years on balance transfer offers. Next I paid off two student loans that were at 9.75%. Kind of a bummer to have the last windfall from my folks spent in 24 hours.
According to many adverticles on Yahoo finance, you should immediately engage a ‘financial advisor’… 
Does anyone here actually use one?
Yes, when we inherited significant money from my husband’s mother. It’s been a great relief – my husband is phobic about planning and I am constitutionally incompetent so we’d have been in bad shape.
How did you choose them?
To be honest, we just went with his older brother’s estate managers, whom he’d employed for many years (he makes a good bit more money than we ever did). They have been sterling.
Don’t want to seem too sceptical. I am sure there are good professional advisors out there who take their fiduciary responsibilities seriously and work in the best interests of their clients for a reasonable fee.
And some people feel intimidated by the business of managing money.
But there are also a lot of rip-off artists.
For the OP’s case, it seems pretty obvious. Pay off any high-interest debt before doing anything else.
It really depends on the amount. Half a million? I’d buy a modest house (no mortgage) because I worry about rent going up annually. (Does that count as #3? It’s not something I’ve been lusting for.) A million? House for me, some to my kids to pay off student loans and have a nest egg (#5), and some for a nice car for my niece, whose been a tremendous help to my sister and is making do with an old beater (#5). A billion? All those things, and the rest to fight global warming (#5)
We have received two inheritances, one from my wife’s stepmother (who had no living relatives) and one from her stepfather (a 1/7 share of his estate). The first went to pay off our kids’ college loans (which would have pleased her enormously) with a few tens of thousands left over which went into savings. The second went directly to savings.
I don’t have any current debt, but my mobile home is in desperate need of new windows, so whatever money I get would go to that.
Unless we’re talking huge amounts, then it’s a small place near some water for me and enough savings to keep me to the end of my life in a fairly simple lifestyle without having to work anymore. I’d love to travel to a few places, but my body is not going to allow for much of that anymore anymore.
Anything above that would help my family. They are not healthy financially and I’d like to change that for them.
Not an answer to your question, but I recently saw $40 on the sidewalk. I left it there so the person who dropped it could find it if they looked for it. People told me I was stupid to do that!
I’ve picked almost $200 that was blowing away in a Costco parking lot, leaving it would have been insane. Then I saw a girl walking thru the parking lot crying because she dropped her money. Scammer, maybe. But I gave it to her and she was quite happy. You should have picked it up and waited around for someone searching, not letting another random stranger pick it up and leave.
I would agree with them if you thought you improved the chances of the owner finding the money again.
That’s sort of what my wife and I are doing. Doing well. Zero debt. Came into a bit more money. We are not going to blow it all, but will use some of it for a first class vacation. Iceland, Norway, and the a Viking cruise around the British Isles.
My Wife and I have worked our tails off all of our lives. We are DINKS. Anything that is left when we depart this world will go to nieces and nephews.
With a chunk that will go towards animal welfare.
Is it bad that my first thought is “Be sure to declare it on your income tax return, assuming it’s not an inheritance”? If you literally find money that wasn’t yours before and keep it, it’s taxable income. The court case to illustrate this in school was someone who bought a used piano and found far more cash hidden inside of it than what he paid for it. Obviously the previous owner didn’t know it was there, so he clearly hadn’t bought title to the cash when he bought piano. So given that he had title to the cash so long as no one else could be found with a stronger claim, it was income to him. (Which, strangely enough, he initially did, then changed his mind and filed an amended return, and THAT is when it went to court Cesarini v. United States - Wikipedia )
It’s not an inheritance but it is a gift. Gift taxes are paid by the giver. The IRS can go after them.
Well, that’s my take on it. 
This more or less happened to us this year when my wife’s father’s music publisher found her notification of his death and that she inherited royalties and send her a reasonably big check.
We split it among the college funds of our grandkids. The oldest is 7, so there is plenty of time for it to grow,. I think we saved some out for the taxes.