A couple of ideas came to mind for shade plants, oakleaf hydrangea for one---and a lot of other hydrangeas in general, and Lobelia cardinalis. A book I highly recommend and have used in the field many times is 'Forest Plants of the Southeast and Their Wildlife Uses', as it has a lot of native woodland plants that can be adapted for the home gardener....if one can find the plants! More native plant nurseries, I say! ;)

I forgot about Lobelia cardinalis! That grows in our bottomland and although rare for us, we love it for its beautiful red blooms.