As a kid growing up in Sandpoint, Pat McManus' books were introduced early. If he's a strong reader, he might be the right age to start, or they are often fun to read together.
You know, on second thought, maybe, as Gellar and others have suggested, 8 is a bit young for Paulsen's books. I read a bunch of more advanced books at young ages and look how normal I am.
I’m a big fan of Gary Paulsen’s books for kids but I think they are better started around 10-12 depending on the kid. I read My Side of the Mountain before that and probably missed some of it because of my age. Where the Red Fern Grows is a rough ending, but such a great book.
I’m kind of coming up blank on recommendations for 8 year olds though.