Well as our little mystery yellow chick has grown she is definitely not a buff orp...her feet are turning greenish and she's off white with tan/black/ brown splotches scattered throughout. Oh well, more fun colored eggs I guess!
When I got what turned out to be an EE, I was told that it was a white orpington. It didn't have the puffy cheeks when young but she does now. I think waiting and seeing is part of the fun.
