Yesterday I realized with horror that I couldn't find my wallet. I looked high and low. Unusual circumstance... it had a lot of money in it.
As I searched for it, I began to form the suspicion that I'd left it at the automated check-out machine at my small town's grocery store. Small town meaning ~8000 households.
I drove down there to report it missing. They had it. All the money was in it.
When I got home I put 1/3 of it in an envelope and took it back there in an envelope, with a thank-you note enclosed. Should be enough to pay for their annual employee picnic, if they have one.