Always check the pockets before you throw stuff out or give it to the Goodwill . . . I'm in the habit of checking pockets because of my kids, but it's never a hundred dollar bill, just half a candy bar or a bunch of paper clips that would play hob with the washing machine . . .
Especially when going through the estates of the depression era generation. We found a lot of stowed cash here and there among my grandfathers things.
But some found money is just forgotten... In fact, I once almost sold my saddle-seat show jacket and jodpurs with a big wad of cash in it. I hadn't worn it in years, but the last time I did, was at a horse show where I'd frequently walk around with a lot of cash for late entries and stall fees.
The buyer tried it on and stuck her hands in the pockets, if she'd been thinking before she pulled the cash out, she could have gotten the outfit for near free :~D As it was, she was happy to buy the jacket even without the cash in it.