WyoWoman

Galax is the only festival that matches your description. Appalachia Stringband Festival(Clifftop) is July 30 through August 3(although people arrive earlier)but it's in West Virginia.

The Old Fiddler's Convention, Galax is August 4-9 (though we line up for camping at 6:00am on the 2nd) and is in Galax, Virginia just north of the VA/NC border.

I go each year to Galax. You can PM me for more information if you wish.
cheers,
chance