Welcome to shade gardening... Lots of stuff will grown much better where you are now than where you were... Solomon's Seal is one of those plants that will not only thrive but spread... And spread... And spread...
Ferns will love it there, too... Cone flower will love it... Hellibores of all varietie4s will thrive... Keep away fro Euphorbia because it will love it so mush that it will become invasive... For real... Pulminaria will spread, too, but it's a lot nicer than euphorbia... Plus, it flowers...
Mahonias will grow, too...
Every wild flower in the North Carolina Wild Flower book will also do nicely...
Do you have any pines??? I know you have oaks which is "oak-kay" but pines are wonderfull to plant under...
But back to the oaks... Beach trees grown well under them and then you have their golden leaves all winter to look at... Very nice understory tree... Hollies will grow under oaks, too...... Rhodos, too... And, of course, azaleas... They'd rather grown under a pine but an oak will do just fine...