I was going to suggest contacting some of the historical societies in the Virginia area. I know there are several quilt museums (the Virginia Quilt Museum is in Harrisonburg). Williamsburg has a wealth of information on some of these things. The property the quilt was found on can give a clue to the history of the quilt as well. Anyone check county records?
It is a great find. I would check with a reputable conservator before doing much to it just in case.