1849 Jan. 63 The accredited envoy from Middleham Moor..lays him the odds as ‘found money.’
1963 30 Dec. 14 l/1 A Christmas check is found money, conjuring up pleasant extravagances beyond the normal budget range.
2006 (Midwest ed.) 3 Sept. v. 7/6 Treat the ‘found money’ with the same respect as earned money and you'll be happier with your spending decisions.