Before I saw your most recent post, my research came up with two possibilities, both of which now look like long shots, at best:
Payner & Heroy, Albany, NY (ca. 1813)
Phelps & Holland, Northampton, MA (ca. 1827)
As I continue in my research, I am amazed at how many hundreds of silversmiths, silver manufacturers, jewelers and retailers sprang up, then faded from sight, not only in big cities like New York and Boston, but in the smallest and least likely of rural areas. That might apply to the maker (seller) of the spoons you have. But yours have been handed down through your family--that makes them a treasure.