I’d never heard the term before, but JD at A Penny Saved used it today. Coupon Angel is a term that he uses (and maybe more people do as well?) to refer to people who leave an unused coupon for a product sitting on the shelf or near the product at the store. If you, like JD, happen upon one you get a usable coupon for an item. Kinda cool.
I’ve seen it happen but never had a term for it before. Now I do.