Sorry for delay in replying. I did take a photo, which I have now managed to crop. Not good quality, but hope it shows what I meant by not collapsed. Not fallen in on a hollow into itself, but instead that the sides remain quite pert and not eroded into the surrounding earth. I hope this is evident in the distant mound.
The foreground mound has the few stones placed at the roadside end. It seemed that all the ones near the road had this feature. This is what reminded me of the Kennet Long Barrow I saw a few days earlier. These Kentish ones were obviously too small to have crawled into.
The vehicle tracks to each on GE is mysterious. There seems no point in dumping unwanted stones in piles in the middle of a useful field. I would have thought that such tipping may have been done into the borders and perhaps in one spot.
Still confused why the mounds are all the same size, same deliberate oval shape and seem to form a regular pattern in the field. There are lots of horses in nearby fields, so wonder if this is some kind of jumping course for them? Then again the protruding stones would seem to be a nasty hazard?
My bet is modern "druids".