I would stay away from the typical ground covers for a curb-
side bed. You can lessen the degree of angle especially
in the bed by the driveway. I agree with pineapples suggestion
of using the Sedum family. I think, imo, the 'vera jameson'
is so versatile.We use it as a ground cover, or to compliment
smaller boulders or to drape over walls.
Move some of the stones to the curb and plant the sedums
around and between. Good Luck, Johnny