Shennong, the Divine Farmer, is one of the Three Sovereigns and the culture hero who taught the five grains, the plough and the market; the Huainanzi says he tasted the hundred herbs and met poison seventy times in a single day. The materia medica that bears his name, the Shennong Bencao Jing, was compiled around the first or second century CE, though the tradition attributes it to him. He is identified with the Yan Emperor, the Flame Emperor, and his death from a lethal herb is told as the price of the knowledge he gave away.
Modern Practice
He is invoked by growers at planting, by herbalists at the start of a course of treatment, and by anyone learning an empirical craft. The offering is the first harvest or the first cup of tea, and the request is for judgement about what is safe.