Is Convallaria majalis a native to New England? It is not on the natives list.
Convallaria (Lily of the Valley) in the wild occurs through much of temperate Europe, and by some botanists is accepted as an original native of mountain woods from Virginia to West Virginia, North Carolina, and Tennessee. Its roots are poisonous if eaten (used medicinally). Ref. The NYBG Illustrated Encyclopedia of Horticulture by Thomas H. Everett.
Hope this helps.