This grower is sure of this plant identification.
Goat's beard spiraea
Aruncus dioicus (Goat's beard spiraea). This is a clump-forming perennial species. It will produce large fern-like leaves that are easy to grow. The flowers are small white and will bloom in the summer.
Under shrubs, border, mixed bed. Summer interest.
Plants of architectural interest that do well in shady moist ground are of particular interest!