In Lamar Valley, where a lot of buffalo roam, we wandered some of the fields before Lamar River, taking care to stay away from the bison on the *other* side of the river.
We were avoiding bison patties, when I saw them....fur. Specifically bison fiber. I nearly jumped up and down in excitement. DH laughed at me. I picked up a bit of down -- very soft; as well as darker fur (probably the hump fur) which was very very coarse and very very dry.
There were a lot, but most were all matted. But I managed to get some that looked relatively clean and mat-free. I didn't get enough to spin a lot, but maybe if I work it in with other fiber?