Nancy Hanks Lincoln, the mother of Abraham Lincoln, died in 1818 due to milk sickness. This occurs after drinking the milk of an animal that has ingested what plant?
Snakeroot which contains the toxin tremetol. Milk sickness is characterized by severe gastrointestinal symptoms and was common in Midwest US settlers in the 18th and 19th centuries. Incidence has declined recently due to current practice of mixing milk from several different cows.
Snively WD, et al. Discoverer of the Cause of Milk Sickness. JAMA 1966;196(12):1055-1060. doi:10.1001/jama.1966.03100250065022