A site along a brook and wetland near Parker Village - Westford, MA

Up in the Carlisle/Westford area there is a nice little crossroads with open farms and open fields with horses and nicely maintained stone walls. It is a pretty spot. For several years I have been wanting to get into the woods behind those stone wall and I was prepared to sneak in but was stumped: where to hide my car? Finally I figured out a nearby legitimate parking area, parked there and did get into the woods. I followed the edge of a field, but in the woods, and a waterway started to develop parallel to the field's edge and almost immediately there was an oval rock pile, medium sized, down next to the developing brook (the water is to the left in the picture):A few paces further along and the wet had developed into standing water with another pile and a stone wall crossing the water (the pile is left of center next to the water).I crossed the water, stepping on stones of this wall, and continued on the far side where there was one more pile. Here are a couple of views:
In the first view the water is to the right and the pile seems vaguely trapezoidal with the longest side to the right.

All of these piles are built on the ground, well covered with forest duff, and medium sized. I noticed perhaps one more.I am walking north following a bit of a wetland which opened up as I proceeded. There were a few more inconspicuous things as I followed the edge, and then one more pile that seemed of the same basic dimensions as the ones above, perhaps a bit smaller. This is facing north into the swamp:Later I went back to where I had crossed the water and followed the swamp edge around the other direction. There was only one more possible pile, a bit different there, facing a bit more westward:All of these piles are no more than twenty feet or so from open water. The water was not flowing actively.