Shawn- I've seen this too, but don't know for sure what to make of it. If you go to the Rigney board and type in my name on the search thing you'll see a discussion about this. All the descendents of Eliz. Rigney and her brothers have this family story about being CHerokee. These are people all over the US, many of whom do not know each other. I feel like there is probably something to it, just not sure what the deal is. We may never know. Eliz. & Austin were married right around the time of the Trail of Tears, so they would prob'ly have erased all evidence of Indian blood if they had any I'm guessing.
I find the use of the word "quarteroon" interesting as I thought it usuallly referred to people who were 1/4 African-American. Maybe in this context it just means "1/4 not white". I don't know. I have a picture of Elizabeth Rigney and she really does look Native AMerican to me.