I found oyster shells near an old stone foundation in Western Massachusetts about 5 years ago. The foundation is about 15 miles from Catamount https://en.wikipedia.org/wiki/Catamount,_Massachusetts , a village that existed from the late 1700's to about 1900.
The foundation I found appeared identical in construction and size to the ones around Catamount. 2.5-3ft high walls, almost entirely made of rounded stones. There is also a small section of colonial road that still exists that is roughly between the two areas, so I believe they are from the same time period.
I found this foundation when I was on a pretty epic off-trail hike with a friend after Hurricane Sandy. Maybe 3 feet away from the foundation my friend found a piece of what looked like oyster shell, next to a little mound of rocks and soil. We dug through it and found at least 6 shells, a small chunk of crumbly rust and some tiny shards of glass. These looked exactly like oysters to me. Pearl/purple on the inside, barnacled on the outside.
This was before we had smartphones, so I had printed Google Earth views and a compass, so I guessed where we were, marked it on the map, and we hiked out roughly the way we came.
We went back once, to get a sense of how remote the place was. It was roughly 5 miles from the nearest road, but that approach had all kinds of obstacles.
I just can't imagine that someone bought oysters, bushwhacked for hours to eat the oysters at this foundation and leave their shells.
Did I find oyster shells from the 1800's?
Oysters were quite popular, especially in the early 1800's, Oysterhouses were indeed common, and transporting them was therefore common as well. Don't know about Massachusetts, but barrels of oysters would be transported by wagon to inns and taverns along the National Road in its busiest period, in the 1830's-50's, when it was the main route from the mid-Atlantic states to the West. Kegs of pickled oysters ( which seem like a very poor second choice) were found quite far west even before then. But in 1831 Colonel Henry Orndorff, owner of a large Zanesville OH hotel, started importing and distributing kegs of fresh oysters from Baltimore , there on the Chesapeake Bay. In the later 1850's , he began ordering better ones to be sorted out and sent, and those became known by his initials, as "H.O.'s" In the 1840's a special wagon line , the Oyster Line, with special wagons , was regularly making a run all the way to Wheeling, which meant that they could have easily been carried even further by steamboat onto various wharves along the Ohio River and beyond.
Philip Jordan: The National Road