Chickens that lay blue eggs.There are several breeds of chickens---and some mixed breed crosses---that lay blue eggs, including Ameraucanas, Araucanas, and Cream Legbars. The eggs they lay may vary in color from a pale blue to a quite striking sky blue.
Do keep in mind that many American hatcheries are pretty deceptive about what type of chicken you're getting. So you may be getting an Easter Egger (below), but they'll tell you you're buying a one of the blue-egg layers. Sometimes they'll purposefully misspell the name: Americauna, Americana, Aracana, etc.
Not cool, you guys!
Chickens that lay blue or green eggsNot that there's anything wrong with Easter Eggers. In fact, we love them. It's just that there's something wrong with not being honest about what you're selling. Like Easter Eggers, some types of mixed breed chickens may lay either blue or green eggs. In fact, Easter Eggers can lay other colors, too, including brown, pinkish, cream and so on. And it's quite likely that even when you have two or more Easter Eggers laying blue eggs, they're probably laying subtly or even dramatically different shades!
Chickens that lay green or olive eggsSome varieties of chicken lay green eggs only. Obviously, this includes Easter Eggers, above, but it also includes designer crosses.
Favaucanas, for example, lay sage green eggs, but various oliver eggers may lay very dark shades of green indeed!