Yellow dock is incredibly toxic to dogs, but they’re also toxic to humans. It’s quite easy to recognize the yellow dock, as the head of the plant looks like coffee grounds and is brown. Don’t mistake this plant for coffee, though, because it won’t give you that caffeinated effect you’re looking for. People who ingest the plant will suffer from mild poisoning that shows as gastrointestinal disturbances, like diarrhea, vomiting, nausea, and cramps. If someone ingests a large amount of the plant, it may prove fatal (Picture This AI).