Some variety of muscadine (not to be confused with muscat or moscato).
I'm drinking one now, which is what is making feel evangelical enough to write this post. It's a cheap muscadine that's always in the stores, from Duplin Winery. I've never been there - it's in North Carolina, and the wine is called "Magnolia". And therein lies the critical point with muscadines: they're a distinctly Southern wine. They grow very well in North Carolina, actually, and the handful of North Carolina wineries we've visited have had great ones. But the grape peeters off right at the Virginia border. I can get this brand regularly in the stores, but not much more and I'm not sure if that's true for anyone too far north of me.
The grape grows south of North Carolina, but I get the impression the Carolinas are where it does best.
My favorite muscadine variety - one of the most entrancing wines I've ever had - is the scuppernong. Scuppernong accentuate the qualities you find in all muscadines: a resiny, honey flavor. The important thing is, it's not just another sweet white. Yes, it's fruity and sweet. But it's much richer than that. If you've ever had a port-style white that's fortified with brandy or something like that - it tastes like that sort of style, with a gob of honey and a nice fruity white blended in. It always makes me think of leaf piles and Indian summers.