What is the name of this children's chapter book?

I read this when I was in elementary school and I only have pieces of memories from it so I will try my best. It's about this girl with bushy hair and can blend into her surroundings (invisible or like a chameleon) and she can't remember where she came from, but I think she was adopted. Anyway, she becomes friends with this little shepard boy. Later, she went into the woods and found this area that transformed into this fairy banquet kind of a place, but then it dissapeared. Something like humans can't see fairies. Then towards the end, a mob of people are chasing her, and they chase her into this barn (I think) and she hides up on the rafters and tries to blend in to become invisible but the mob sees her and calls her a monster. If I remember correctly she is half human half fairy. Sorry if my memories are a bit skew, but I cannot remember the name to this book and it has been bothering me for some time. Please help me to name it.