Conoclinium coelestinum, commonly called mistflower, is a late summer to fall-blooming herbaceous perennial that is native to the Eastern United States. It is a member of the aster family; it looks like annual ageratum and in that regard is sometimes commonly called hardy ageratum. But it is perennial and can spread aggressively by rhizomes. It grows 1-2' tall and easily grown in average, medium to wet, well-drained soils in full sun to part shade. Prefers moist, fertile, humusy soils which do not dry out.
 
Native throughout NC- click to see it's range in North Carolina
 
More info here - NC St. Univ. Plant Toolbox