In On The Banks of Plum Creek, the book takes place in a town that Laura Ingalls Wilder never mentioned by name. That town is Walnut Grove, which is located in Minnesota and it actually is a real town.
Today can go visit Walnut Grove and see a replica dugout, as well as a museum and gift shop where you can purchase books and other Laura memorabilia. You can even view the church bell that Charles donated his last dollars to, the money he was going to use to buy new boots.
Walnut Grove is also portrayed in the Little House on the Prairie TV show, but again that town as portrayed on the television show is quite different than the Walnut Grove it existed in real life.