Much depends on how much sun the berm is exposed to- and how much water the ground will receive under the boughs of the pines- and then- what your likes are- >Bishops weed, ajuga, archangle lambium, seedum, thyme, daylillies, ferns, sundrops, monarda, phlox, crown vetch, ranunculis, sedges, vinca, from stepables to easily spreading and reseeding plants, there is a world of choices available- and many can be gathered at other gardens- I would suggest you make a choice and ask for some- swap or otherwise- that is the nature of ground covers- all too soon there are too many and one must remove them to somewhere..... I have several that there is more than enough to share!
Happy researching!
Julie

Julie helped me out last spring as well as others in the group. I have some sedum if you want any. It is hard to plant anything under pines though.