I rarely buy produce at Wal Mart because while the price is right, the quality is usually poor.
However, if I'm there I'll always swing through just in case something good is on sale (eg, fresh raspberries).
Today while on the berry hunt I found these babies: concord grapes, I've also seen them called champagne grapes.
They're super small and super sweet. The pic to your left is to give you a size of their scale, not to suggest you eat them with PB, but if that floats your boat, go ahead.
I love grapes and these are my favorites, by far. And I rarely can find them, I would suspect they're highly seasonal and they come in a 1-lb plastic box to protect them because they're so delicate.
I chanced the purchase due to WM's produce rep, but they were very good. I'm heading back tomorrow to get more as I'm not sure how long they'll be in stock.
If you like grapes, try to find these. I know Trader Joes would carry them from time to time, too.