Kenyon's Grist Mill in Rhode Island makes a range of stone ground meals. Their white corn meal is the best I have tried for making RI johnny cakes. Whole Wallet used to carry them, but they have dropped the product and I am looking for a new source in Massachusetts.
The company is still very much in business
so it is simply a question of tracking them down locally.
I suspect that the gift shop in Old Deerfield might have it, but probably at a price that matches the real estate in that inconvenient neighborhood. So I would prefer a store in the Northampton-Amherst-Springfield area.