Harper Element has been publishing a lot of nonfiction about abused foster children. They're all from the UK, but they're being sold in the U.S. now, probably for the first time. Many of them have been introduced at bargain prices -- I learned about one of them here.
Here is a free short book by Casey Watson, one of the most popular (and prolific!) authors:
Just a Boy: An Inspiring and Heartwarming True Story