I recently ran across a neat website, paganchildrensbooks.com - they're an online indie bookstore that specializes in, as their name says, books for Pagan children. While they don't have every book I've found for Pagan kids, they have a ton of books I'd never heard of, which is quite cool, along with games & other Pagan-y things.
It's nice not having to try to figure out what might be Pagan and what might be overtly Christian, which is frequently what happens when I'm looking for books for Acorn and Leaf online. I don't mind a few minor references here and there, but clearly we need opportunities to teach our kids our beliefs and values, because so much of the mainstream world (most caregivers, teachers, playgroups, and the like) is going to teach them about Christianity - at least, the generic version of it.
There still aren't many books for the 0-3 age range here, but I'm having a hard time finding those anywhere. Sigh.
Obligatory disclaimer: affiliate link here, but the opinions are mine. I get money if you buy stuff following that link - given the amount I'm spending on gas to head to the hospital every day, every penny helps!