From Seed to Tree is a wonderfully gentle and fun way to introduce young children to yoga. This book takes you through the life cycle of a tree using your body and breathing. It is a fun way to have an exercise and reading break with your child and also a great sequence to use in a toddler or children's yoga class.
I came across this while looking for something else and was entranced by it; it does pretty much what you might expect from the title, with engaging text and illustrations.