American gamefowl, Shamo, asil, old English game, etc. If she is a game mix, I’m guessing it’s American game, since those can have small crests (they’re called toppy gamefowl).
She could be a game mix. She’s most likely not an ex-battery hen, since they use specific breeds or crosses, such as production white leghorns or red sex links. Crested breeds and mixes of crested breeds aren’t usually known for their egg-laying abilities.