I absolutely love the book Kids Knitting
by Melanie Falick. I did learn to knit as a child, but forgot how, and I used this book to reteach myself a few years ago. And now I'm using it to teach my six-year-old.
Melanie Falick also has a baby book that teaches you how to knit. I didn't teach myself from it, so I can't vouch for it in that way, but the projects are just gorgeous.