Where I Belong - Mary Downing Hahn

No one is kind to sixth-grader Brendan Doyle: his foster mother, his teachers, his classmates, and especially the thugs who bully him. He takes refuge in books, drawing, carving, and daydreaming. When Brendan stumbles upon an old man near his tree house in the Virginia woods, he is quick to believe that this is the magical Green Man, guardian spirit of the forest. Brendan's need to immerse himself in his fantasy world becomes more acute, until he meets a girl with secrets of her own who may just keep his feet on the ground.