Here are a few children's spiritual books. Not trying to expound on the mysteries of the Unmanifest here, just trying to teach a few life lessons and perhaps help the kiddos retain a bit of the openess they were born with.
Zen Shorts and Zen Ties by Jon Muth: A giant panda with a Zen outlook on life walks through the superb illustrations of these slim volumes recommended for ages 4 to 8. Lessons about befriending others and selflessness abound.
Moody Cow Meditates by Kerry Lee MacLean: A clever way for little ones to let their mind relax from anger by learning to recognize the thoughts, then literally watching sparkles settle in a jar of water (directions for creating such are in the book). Recommended for ages 4-8.
Just Like Heaven: A Mutts Children's Book by Patrick McDonnell: Mooch the cat and Earl the dog show that any place can be heaven depending on our perspective. For ages 4-8 and parents of any age.
Kindness: A Treasury of Buddhist Wisdom for Children and Parents by Sarah Conover and Valerie Wahl. Traditional Buddhist tales shortened a bit for children. In the "Monkey King," for example, a palace monkey is returned to the wild where he illustrates the selfish and unkind ways of men. Recommended for ages 9-12. Vocabulary is a bit heavy, so definitely one to read together.