I thought the name may have had some roots in the Pallasgreen/ grian or sun goddess. However from the Gaelic for Rosegreen, it seems that it literally means rose green.
This mound is just off the R686, there is a church across the road that looks like it may be built on a low mound. Perhaps they are both barrows. The field this mound is in is up for sale for a housing development so this may be the last we ever see of it.