They're not crosses of specific breeds. Hatcheries keep breeding flocks of Easter eggers. Not Ameraucana, not Aracauna. The breeders are mixed color birds who usually have genes for blue or green eggs. They often have pea combs, beards/muffs, green or dark legs. These aren't universal traits, they're just common factors with hatchery Easter eggers. Sometimes you'll get a clean faced bird, or one with a straight comb, etc. Egg color can be all over the place.