I genuinely just am interested in MN responses as to what you should or would do in this kind of situation!
If you found a £20 note on the floor in a supermarket, with no one nearby who it was obviously from, would you pick it up and keep it?
What about if you found it on the ground in the middle of a park, with again no one nearby who it was obviously from?
Just the note alone - it's not part of a wallet or purse!
(It's not really an AIBU is it- AIBU to wonder what you would do?)