These books about the Oregon Trail and early pioneers were recommended by someone I know who particularly enjoyed studying this time period with her children. Although she wasn’t specifically homeschooling according to Charlotte Mason’s principles, she did have a high regard for the literary value of good books.
I can’t personally vouch for these specific titles, but if I were starting a study now on the Oregon Trail, I would definitely begin here for ideas. Also keep in mind you don’t have to read ALL of these books. Pick a couple that interest you or your kiddos. My friend who recommends these titles spent a complete school year on nothing else but the Oregon Trail. They made an entire year’s worth of interdisciplinary studies around this one topic. Your mileage may vary. 🙂