tel jetson wrote:
creeping thyme has never caused me any problems, but I don't live in PA. along those lines, more aromatic and flowering herbs seems like a good choice. there are plenty of other interesting thymes. thyme is handy to have around for bees, who use it for medicine. that includes honey bees and the rest of the bee gang, too.
I also like lupines, Fragaria chiloensis (can get out of hand), day lilies. camas.
arctic raspberry (Rubus arcticus) might work. cloudberry (Rubus chamaemorus) is another low raspberry, but it's sensitive to heat. there's a hybrid (Rubus arcticus x stellarcticus) that could work, though it isn't easy to find and also has trouble with heat. those three are low ground covers with fruit. the flowers are nice, though not that showy.
how about trefoils (Lotus corniculatus)? nice flowers, low-growing, nitrogen.
so many options. how about some more criteria to narrow it down? maybe be a little more specific about what you're trying to accomplish.