Anemonella is a genus in the Ranunculaceae family with one species from Eastern Northern America, Anemonella thalictroides. This is a woodland plant with tuberous roots that blooms in the spring.
The first three photos by John Lonsdale of this species and the next five of named cultivars.
A. t. 'Betty Blake', A. t. 'Don Hackenberry', A. t. 'Grand Ridge', A. t. 'Green Dragon', A. t. 'Scoaffs Double'