The Cowboy Sam series by Edna Walker Chandler, was originally published in the 1950s and 60s. Unfortunately, I only own one of these. I believe they got new life in the 1970s reprinted with color covers.
This is what opened me up to book series–about sixteen of them—my favorite being Cowboy Sam and Porkey (about him and his horse), Cowboy Sam at the Rodeo, and Cowboy Sam and the Indians.

Each story was a little harder than the last to read, as I remember it anyway. It was the 1960s so there were a lot of westerns on TV. I grew up in the city of Buffalo so my appeal for these I think was the outdoors, horses, cows and space. It opened up my interest in Native Americans different from the TV image of them and is one of my biggest focuses of my non-fiction research and writing. I live in a rural village where the county’s claim to fame is having more cows then people and I see horses on every drive–not a cattle drive, silly, I meant in my car.

It is part of my all tive top five books listed here http://historysleuth.org/2013/03/childhood-books-shape-your-life/ ( )