Amanita smithiana, also known as Smith's amanita, is a species of agaric found on soil in coniferous (Abies, Tsuga, Pseudotsuga) and broadleaved (Alnus, Quercus) woodland in the Pacific Northwest of North America.
Ephraim Chambers, in his 1728 Cyclopaedia, says "Mithridate is one of the capital Medicines in the Apothecaries Shops, being composed of a vast Number of Drugs, as Opium, Myrrh, Agaric, Saffron, Ginger, Cinnamon, Spikenard, Frankincense, Castor, Pepper, Gentian, &c".
He frequently visited his friend and fellow mycologist T.J. Wallace in Membury, Devon, publishing a number of new agaric species from Dawlish Warren and other Devon localities.
In writing about the shamanic rituals of the indigenous peoples of Siberia, he noted their use of the fly agaric mushroom (Amanita muscaria).