This might already exist, but I didn't feel like sifting through the massive amount of discussions.
When I was a kid, I almost exclusively read Pippi Longstocking books by Astrid Lindgren.
I didn't broaden my horizons much for a long time, but I read all the Little House on The Prairie books in 3rd and 4th grade. I mainly read school material until 6th grade, which is sad. But hey! Better late than never!