Bison. It's the original American grass-fed meat. Before cows came to this continent, enormous herds of bison roamed the Great Plains. After a long period of decline, there are now hundreds of thousands of bison living on ranches in North America. Although conservation efforts helped restore the herds, it was Americans' acquiring a taste for bison that brought the numbers back.
For the record, bison is not buffalo. Although members of the same scientific family, bison are native to North America. Buffalo are a species native to Africa and Asia.