Wellfleet, Cape Cod, MA is well known for their big, delicious oysters. This species Crassotrea virginia is large in comparison to other oyster species. The best part is that they are easy to catch - during low tide, you just have to walk along the shore and pick them up, no digging required. The state does require a permit though.
Other popular species include; Blue point, Apalachicola and Malpeques. While all are tasty eastern varieties, I prefer Wellfleet.
Henry David Thoreau
also has a chapter of his book Cape Cod
titled, The Wellfleet Oysterman.
Wellfleet has amazing beaches too, but no seaglass there.