Here's a quote from famed folksinger Alice Gerrard:

"Every time I go up I-95, I cross over the South Anna River. I've always loved that name. And I put it together with something Libba Cotten told me years ago. She didn't want to be buried in the ground. She had an image of herself that she'd be laid on a river. She would float down river and all her friends would be standing on the bank waving at her as she went by." (News and Observer, May 10th, 2013, p. D3

I can't find anything to suggest she actually had the latter half of her wish carried out, but it seems to lend a lot of credence to the earlier claims that she was not, after all, buried.