According to what part of the state in SC and NC you live, if you have mater plants in ground, you might want to cover them Sunday and Monday night. Temps in low 40's forecast. Of course that could be even lower in actuality.
Last year I lost some of plants when it got to 39-40. They were not even in the ground but still in the little pots they came in and were under my carport.
I went back to the place I bought them to replace them, and every one he had which were 2000 under a large outdoor covered roof area had been killed. I did not realize young plants would die at 39 and 40 degrees. There was no frost.
Beans, corn and okra like warm weather but can stand a little more cold. Temps in the 30's will leave them with some leaf burn but they normally recover quickly.
Potatoes, onions and most greens (collards, etc) are considered cold weather crops. You get them in the ground in February so they can finish bearing before the real heat comes. They wither when the temps close in on 90.