Tall Bellflower, a native species, has been added to the USWildflowers database (07/28/2010.)  Scientific name is Campanulatstrum americanum, and may be more commonly known by the synonym Campanula americana.  This plant also is known by the common name American Bellflower.  Photo below was taken near Waynesville, NC, on 07/12/2010.

Tall Bellflower, American Bellflower – Campanulastrum americanum