http://www.geocities.com/ace_of_nitwits/Enigmas.html has some info on the stone circle, which along with a stone row constitutes the Cefn Gwernffrwd group (under which name they appear on the Portal).
Stone circle SN73714936, stone row SN73704935-73724942. Bronze Age ring barrow SN73704942 probable duplicate SN736493 as ring cairn - different sources, the usual CARN stuff. Dolyddlan possible standing stone SN73764696. Round barrow SN73684985.