I thought a first walk after the snow would be better to the south, and picked an un-explored piece of Hopkinton State Park: the headwaters of a couple brooks at the northeast foot of Saddle Hill:
I found a small mound at the lower left edge of the large red outline, and a seat/enclosure in the middle of the lowest red outline. The blue outlines marked where I could cross the road without being in someone's yard. The outlines to the right did not get visited as I went, instead, to visit the "picnic" sites just east of there. The impulse to go to where the water starts was correct and, had I been systematic, would have brought me eventually to those main 'picnic' site. But I knew about that and was interested in the bits of woods west of the main road.
Minor finds:
I would have missed this except my plan called for skirting the wet areas and so I turned slightly here and, at that point, noticed a small mound.
I was having a conversation with myself about how I did not need to see the pile because my feet brought me to it anyway and it is easier to notice things when you are stepping on them. Not too competent searching, but it worked out with the aide of reasonable planning. The next item was more noticeable and also part of the plan to follow the brooks inside those red outlines. This is in the southernmost one:
These features are similar to ones at College Rock.