I found 20 bucks on the ground, picked it up, walked around to see if anyone lost it. No one did and I kept it, ended up buying food, drinks and pens, lol
My wife picked up a 100 dollar bill in a casino. She asked me what to do. I told her if she asks who lost it there would be more "losers" than she could imagine. I told her to play it away...she did. Had it been a credit card, wallet anything that would get it to the rightful owner of course we would have turned it in...