An Egg Is Quiet by Dianna Aston, illustrated by Sylvia Long.
I love beautifully illustrated nature books and this is one of the best. Ms. Aston provides some simple text and more detailed observations about specific kinds of eggs while Ms. Long's realistic illustrations complement it well. The book covers all sorts of eggs: insects, birds, reptiles, even fish. It's just an introduction, of course, with much left to learn, but it's fascinating and provides much to examine at leisure, especially on the end pages. The first few show eggs of all shapes and sizes while the ones at the end of the book show all the animals that emerge from those eggs.
For those that limit children's exposure to the theory of evolution, be warned one of the egg facts is on fossilization and covers "creatures that died millions of years ago."
I've requested A Seed Is Sleepy and hope it is just as wonderful.
By the way, we also have Chickens Aren't the Only Ones and enjoyed it.