I wondered about Buttercup when I saw his comb, but I didn't know if any other breeds carried that trait. He does have just the 4 toes. He's a very quiet and gentle bird .
Thank you both for replying. It's interesting to find out what some of these mixed birds are. I really like his spiky little crest. My DH calls him "Dragon" instead of Henry Now I can tell him that Buttercup and Dragon would definitely cancel each other out.
I'd say he doesn't have buttercup in him, rather he is a Polish cross. Crossing a Polish with a straight combed breed often yields a comb similar to a buttercup.