Canada was the only Rigsby in White Co in 1820, and in 1830 only he and Warren were there. Canada had a daughter I haven't been able to identify. I have that she was born about 1816, but I'm not sure where I got that. The census shows her under 10 in 1820, and 5-10 in 1830, which pretty much means she was born in 1820. She was not with Canada on the 1840 census.
Warren had two daughters born between 1820 and 1825 I haven't identified, but his wife was born about 1807 and so is unlikely to be the mother of your Margaret.
One thing that makes me hesitate is that you say she was married in MS. As far as I know none of Canada's family left TN. The only Rigsby family I know of in Lowndes Co was an Absolem, who I'm fairly sure was really a Rigby. White Co and Lowndes Co are fairly far apart, and I don't know what Margaret would be doing that far away. Are you certain of the marriage place? Or do you know of some story that would explain why she married there?
I also don't know of any Indian on that Rigsby branch. If Margaret was an Indian, it could be that she just took the Rigsby name and is not really related to the family.