The Fields of Home is the fifth book in the Little Britches series.
From the 2001 audio book:
The fatherless Moody family moves from Colorado to Medford, Massachusetts in 1912, as Ralph enters his teen years. He tries as hard as he can to be a "City boy," but without much luck. Little things that would have been just fine in Colorado are always getting him in trouble, so he is sent to his eccentric Grandfather Thomas's farm in Maine.
With his Grandfather's cantankerous ways, an "onery yella colt's stubbornness," Uncle Levi's wise gentleness and the pretty girl next door's kindness, young Ralph manages to find a whole new set of adventures...
Mary Emma & Company
Shaking the Nickel Bush