I found an inch and a half long intact grasshopper* in my tub of brand-named arugula today.
What surprises have you found in packaged food?
*Deceased
Thread title makes a great Love song
Many years ago I was drinking a carton of flavored milk and, towards the end something solid tapped my teeth. I opened up the carton to find a tiny, pasteurized, homogenized, chocolate flavored frog.
Back in the early 80s my Dad was eating a Bounty bar (Google tells me that the US equivalent is a Mounds bar) he bit off half the bar in one bite revealing the back end of a fat beetle sticking out of the other half. He wrote to the company to draw their attention to it and received a nice apology letter and a complimentary box of assorted Mars products. As kids we got to enjoy them as dad wasn’t keen on chocolate for a while.
Mid 2000s I worked at a company that had a coffee machine filled with pre-packed “Maxpax” type of cups, a colleague drank her coffee down to the dregs to find a freeze dried bluebottle fly swilling about the bottom of the cup. She didn’t seem to be that bothered either which seemed funny at the time.
I found a live ladybug in my bagged salad once. I just washed the (prewashed!) salad and served it.
2_More_Bits, “There’s a Grasshopper in my arugula.”
Grocer, “Quiet down, or everyone will want one”.
Bartender: “You know, we have a drink named after you.”
Was it crunchy?
I admit I would be pretty disgusted to find a leaf of arugula in my tub of grasshoppers, but then I really hate arugula.
Found an intact 5/16" nut in a jar of Safeway store brand raspberry jam. Got two 35 cents off coupons from Safeway when I let them know. Took the nut and partial jar of jam to my local Safeway and showed the manager. He gave me a $100 gift card.
Rat bone.
Years ago, when I was a kid, I found a dead nightcrawler
in a loaf of store-bought bread.
This doesn’t really count since it didn’t make it to the stores but kind of interesting anyway.
Years ago, I was doing some service work at a frozen pizza factory. I had to disassemble an item that was a little too complicated for the production floor so they set me up with a spare desk in the quality assurance office. On the wall was a piece of poster board with a bunch of stuff taped to it. They were items that the metal detectors had found at various stages of production. There were nuts and bolts and nondescript chunks of metal like you’d expect. However, there was also a LOAD of shotgun pellets. Apparently, some people like to shoot at cattle 
As a single-digit child I had a slice of store-bought cake (i.e. from the supermarket’s bakery – I don’t remember whether it was a birthday cake) that had a flattened crane fly on the bottom of it.
I once ate a blueberry, and it crunched as I bit into it. I spit it out and noticed that there was a beetle inside the blueberry.
Can’t think of anything gross I ever found, other than (two times now) settling down at the computer to enjoy my Whopper and fries and Coke Zero, discovering that the Coke Zero was actually root beer! Blechhh!! 
Back when I would occasionally keep Swanson TV dinners on hand for a quick lunch or dinner, I once opened up a fried chicken dinner. There was nothing gross inside at all. One little section of tray had mashed potatoes, another little section had corn, and the big section for the fried chicken contained … nothing at all. Perfectly sealed tray, perfectly clean large section for the chicken, just nothing in it!
I like to buy whole heads of hydroponic lettuce, and every once in a while I find a teeny tiny snail in one.
I once lived in Oaxaca, Mexico, where roasted, salted grasshoppers are a delicacy.
(Well, they’re usually more of a bar food, like pretzels or salted peanuts).
Oh, I remember another thing. I brought a cheap-o frozen dinner for lunch once. I cooked it, and it was rotten! Smelled up the kitchenette, and I didn’t have lunch. I bought it frozen, but it must have thawed out at some point at the store. Gross.