Purple Prairie Clover (Dalea purpurea) - a perennial herb that blooms in mid-Summer with purple flower tuffs on long stems. 
 
Growth: Can grow 8” to 35” tall.
Light: Prefers full sun.
Soil: can grow in prairies, rocky glades, or open woods. Soils range from clay loams to loamy sands.
Hardiness: moderately drought tolerant, & fairly fire & shade tolerant.
Maintenance: self-seeds locally
Benefits: Attracts pollinators.