I have never once had that happen, and I've done literally thousands of gas stations. I need to start looking down more!
I rented a car in Savannah last week and went to put my sunglasses in the holder thingy in the ceiling. When I opened it there was a receipt in there and a $10 bill wrapped in it. The receipt was from April!
I did not donate it to charity.
It's been a while since I found cash at a station shop. Though I did find someone's driver license last week (turned it in to the cashier). Gut feeling says the money is from lotto customers who have no idea how much they just spent in the store that they don't even realize it, and dropped it thinking it was a losing ticket.
I always put money I find in to charity. And for what it's worth, the cow that my leather wallet is made from was named Charity.
When my kids were little they found money all the time. Probably because they were closer to the ground. Thanks for the reminder to keep looking!
Edited to add: Not to mention that I don't know if I could sleep well at night finding someone's diamond ring and keeping it....