Carvings of Psilocybe mushrooms in St. Michael’s church in Hildesheim, Germany and the church of St. Martin de Vicq in France are so well done that the species can be identified. Psilocybin cubensis is depicted in early Christian art. Also, in the church of St. Martin de Vicq, there is a fresco on a wall showing Jesus entering Jerusalem and being greeted by people holding psilocybin mushrooms and not palm leaves.
This information is discussed in depth in the 2017 book “The Psychedelic Gospels: The Secret History of Hallucinogens in Christianity” by Jerry and Julie Brown.