I recall reading a book from the library titled "Alison's Day" or something similar. It is a photo journal about a girl who unschools. You may have to ask a librarian because the title may not be right, I couldn't find it on amazon, or maybe it is out-of-print. It would be good for the kids under 8.
Here is a link with books for older kids:
http://www.gomilpitas.com/homeschooling/olderkids/OlderKids.htm Others:
And the Skylark Sings with Me: Adventures in Homeschooling and Community-Based Education
An "A" in Life: Famous Homeschoolers
Real Lives: Eleven Teenagers Who Don't Go to School
Teenage Liberation Handbook: How to quit School and Get a Real Life and Education
YOu have the Little Bear Series, not specifically about kids homeschooling, but most ppl are convinced Emily and Little BEar are both unschoolers.
Hope these help!
Meg