These are my daughter's recommended reads for kids in fourth grade. They were her favorites when she was that age. They're real life fiction, historical fiction and fantasy.
The Birchbark House by Louise Erdrich
Blood on the River: James Town 1607 by Elisa Carbone
Each Little Bird that Sings by Deborah Wiles
The Golden Compass by Philip Pullman
Harry Potter and the Sorcerer's Stone
Harry Potter and the Chamber of Secrets
Harry Potter and the Prisoner of Azkaban
Julie of the Wolves by Jean Craighead George
Midnight Rider by Joan Hiatt Harlow
My Side of the Mountain by Jean Craighead George
See also Sandra's Recommendations for Third Grade Readers.