I have always liked "scoots" as I call them, the varied species of Scutellaria. Many are excellent plants for the rock garden, some can be aggressively spreading by stolons (so be forwarned, do your research), and there are well-behaved tall types suitable to the perennial border or wildflower meadow garden.
I was given a plant of Scutellaria incana by a garden visitor, and it turns out to be a highly ornamental plant, now among my favorite scoots. The species is native to much of eastern USA, found in 3 different varieties (var. incana, var. australis, var. punctata); I'm assuming mine is var. incana.
While it does grow 1.5 - 3' tall (mature plants can reach 4'), it an elegant plant of refined growth and leafage, valued for the super long display of flowers July through September (mine continue into October, witness my photos) when few other herbaceous plants are flowering, followed by an autumn show of whimsical purplish red seed pods. This plant has it all going on.
I show photos of a young flowering plant in 2008, and a couple views in 2009 after the plant put on lots of growth and numerous spikes of bloom. For further photos and information, including range maps, check out the links provided.
an alternate distribution map (click on map to enlarge):
Rob's Plants (some good images)
Image from University of Texas at Austin