Polypodium virginianum; Polypodiaceae
There are a few native ferns that are evergreen: ebony spleenwort, some of the woodferns (Dryopteris species), Christmas fern (in milder winters). I’ve seen a few around but haven’t been able to identify them. Rock polypody is pretty easy, though. I love how it grows right out of stone, needing very little soil. Being a fern, of course, it won’t flower, but here’s how it looks in mid July:
There are vast stands of it on the rocky bluffs around Carderock.