Personally, I'm a big fan of the Turks cap hibiscus (malvaviscus arboreus).
It rapidly covers ground, and blooms and blooms...
I've found that a ton of traditionally full sun plants will positively thrive in those areas where you have straggly looking turf... The sooner you get that stuff shaded out... The better your garden is going to look....
There are tons of spring ephemerals, like virginia bluebells and atamasco lilies, and bloodroot... And while there's definitely a place for those in a southern shade garden... You are probably going to want to plant stuff that has more of a presence like a collection of native ferns...
Ruellia elegans is another ground covering red flowered plant that I like for an area like yours...
There are just so many plants that would fill your area that I'd need to walk through one of my shade gardens to make good recommendations...
But... You first need to bring in several dump loads of mulch.... Before planting anything.
