From Longman Dictionary of Contemporary Englishfinderfind‧er /ˈfaɪndə $ -ər/ noun [countable] 1 FINDsomeone who finds something that was lost or stolen The finder usually receives a reward.2 → finders keepers (losers weepers)
Examples from the Corpus
finder• Herons are consummate finders and catchers of fish.• I was her finder, and she needed me.• During both days, tokens were buried and prizes were given to the finders.• The finder of the Stone shall have great riches and joy for the rest of their life. 