From John B. Boyle and Evelyn W. Moyle's Northland Wildflowers

White Snakeroot (Eupatorium rugosum) Description Perennial of shady places. The branched stems, usually 2 to 3 feet tall, bear opposite leaves with toothed, oval blades and flattish clusters of pure white flower heads. Summer, autumn Habitat and Range Minnesota: mostly in hardwood forests of the south; general: eastern temperate North America. Comments The herbage contains trematol, which is poisonous to livestock and is excreted in cow's milk. Such milk, if consumed by humans, causes "milk sickness." This is the disease from which Abraham Lincoln's mother, Nancy Hanks, died. In pioneer times cattle were often pastured in newly cleared woodlands, where Snakeroot thrives.
Purple Coneflower
Bouncing Bet