I used a great site about buffalo hide stories found on the Smithsonian's website. It was about Winter Counts (calendars). I also found video of an artist painting on the buffalo hide and describing his technique and symbols.
Found the video on this great site: Prairie Edge
After looking at these, I gave my kids a list of Native American symbols and had them "write" a story using only pictures. This was tough for them at first, but they quickly got the hang of it. After drawing their symbols on brown construction paper blobs (cut in the shape of a buffalo hide, of course), the mounted it on construction paper, and wrote our their stories in words. These were great to display in the halls during parent-teacher conferences! The kids did a great job with this project, and I've received many compliments from parents and teachers.