What is the best thing you've found while running?
Back in the 80's I picked up a class ring that was in the street, smashed beyond repair. On my way home I stopped at one of those schlock pawn shops that had a "We Buy Gold" sign in the window. The guy weighed it, and offered me $10. He might have screwed me over, but I ran home happy with the 10 bucks I didn't have before. This was back when gold was about 1/3 of what it is now.
Occasionally I'll find a dollar bill in the ditch. Experience tells me that if there's one, there is probably more. Last month I found a dollar, looked a little more and found 3 more nearby. If I'm doing a run for time, I don't stop and look, otherwise, why not?