The Sea of Grass was first published in 1937 by the Curtis Publishing Company and reprinted in 1965 by Time Incorporated. The author is Conrad Richter and the book was made into a movie in 1947. Off hand, I thought the book would be about the plains, Kansas, Nebraska, Oklahoma, etc., because that to me is the Sea of Grass, but it actually takes place in New Mexico Territory, where Richter moved from Pennsylvania to Albuquerque.
Seen through the eyes of his nephew, it's the story of a cattle rancher who marries a woman from Saint Louis (a mail-order bride?) and struggles against the homesteaders who want to settle on his ranch land. The antagonist is a handsome lawyer, who uses the courts to help the homesteaders and is a friend of the President.
Richter was reluctant to begin this novel, having been a children's author and short-story writer until then, and didn't know whether he could do it or not, but some say the result was classic. To me, the language is eloquent, poetic, and literary, as if he had wrenched each word out of the hands of the "word keeper." And it's short, only 118 pages.
I guess the movie was less than eloquent, and I don't remember seeing it under the title "The Sea of Grass," but the actors were Spencer Tracy and Katharine Hepburn, and a detailed review of it can be found here: answers.com/topic/the-sea-of-grass-film (with a click on the mouse).
I caught the tail end of a documentary, Cowboys and Outlaws, on the History channel this AM that had an example of the subject of this novel where some ranchers lynched a woman (Cattleman Kate, they called her) and her husband for homesteading on land claimed by a cattle rancher (Boswell) in Wyoming, who distorted the facts and had it in the Cheyenee newspaper to his favor, claiming she was rustling cattle. An eye witness neighbor and her stepson were found dead under mysterious circumstances. Later, they found a bill of sale for the cattle she owned.