I buy my grits from Geechie Boy Mill on Edisto Island. Delicious and not so pricey as Anson Mills. I freeze my grits. Geechie Boy doesn't sell the range of products that Anson Mills does, but they have added rice, sea island peas, blue popcorn and some other products.
It never occurred to me to freeze popcorn, but that's interesting. We buy popcorn in smallish amounts and it doesn't sit around too long.