Our native plant success story for this spring is ruellia (whether humilis or caroliniensis, I'm not sure), commonly known as wild petunia, even though the plants aren't all that closely related. But while petunias generally languish for me (probably because they want things like regular watering and feeding), ruellia has taken off. The single plant given to me in the spring of 2011, allowed to go to seed, has now colonized both sides of our front walkway, but it's so delicate-looking that no one (probably) could call it invasive. (As much as I like blue-eyed grass, I am beginning to lose my enthusiasm for a plant that pops up everywhere, looks good for a month, and then proceeds to get depressingly tatty. I am actually cutting off and disposing of the seed heads of this native plant.)
Ruellia, however, blooms for a much longer period, and besides being lovely and low-maintenance, is pollinator-friendly. As low to the ground as my plants are (probably because they are grown in pebbly sand next to a concrete walk and rarely watered), they attract hummingbirds, and they are listed as hosts for the the larvae of Buckeye butterflies, among my favorites. Some ruellia are endangered in the wild in neighboring states, but nobody gave that depressing news to the plants in our yard.