I sent you a longer PM but in case others are reading:

The companion book to Parenting Beyond Belief is called Raising Freethinkers. It's a great book with questions that kids ask, answers for humanist, Unitarian, atheist and agnostic families and tons of activities to do with kids that develop the moral roots in a secular way.

You can also look into D'Aulaire's Book of Greek Myths, the DK Book of World Religions, lots of picture books on evolution, etc.