The B+ magic mushroom is a Psilocybe cubensis, a species of psychedelic mushroom. Its main active elements are psilocybin and psilocin. The p. cubensis species is the most known psilocybin mushroom. Their status is established because of p. cubensis are widely distributed and very easy to cultivate.
like most other psilocybin mushrooms, the dosage would start at around two grams dried.