A great site, although I’m a bit unsure of the restoration techniques on Anglesey, an overuse of bricks me thinks. But it’s one of the sites that they can be easily ignored.
There is a small stone further up the road from the chambers in the opposite direction to Ty Mawr approx.SH259801, it stands on a small mound with a few smaller loose stones around it. Not O.S marked, so it may be nothing.