We did report the poppy stone to Coflein but I think the stone they refer to at Pen y Rhiw Iar is this beast (now strangely corralled):
http://www.themodernantiquarian.com/site/8966/cefn_gwenffrwd.html
It is right on a boundary between parishes I seem to remember
Here is another whopper standing quietly in the trees by the possible stone row:
http://www.themodernantiquarian.com/site/8964/ty_newydd.html
Felt like they were all on a route from the tomb at Gelli:
http://www.themodernantiquarian.com/site/8320/gelli.html
to the complex at Cefn Gwernffrwd
http://www.themodernantiquarian.com/site/8971/cefn_gwernffrwd.html
It is truly is a wonderful locale - very much looking forward to trekking up to see Bryn y Gorlan.