That renews my faith in humanity.
I once found a very pretty ring in a nonprofit needlework shop. They also sold locally made gifts, and the ring was next to a sample container of hand lotion. I took the ring up to the counter, saying where I had found it; obviously, someone took it off to try the lotion.
The (very nice seeming) lady behind the counter said, "What a pretty ring. I'm going to keep it!" I was shocked I should have told her, "Nevermind; I'll put an ad in the paper." (Long before the interwebs...)