In nearly all cases, yes. Psilocybin and psilocin are listed in Schedule I of the Controlled Substances Act, making it illegal to cultivate or possess psilocybin producing mushrooms for either personal consumption or distribution.
However, they can be used for scientific research under tightly-controlled conditions with a special license from the Drug Enforcement Administration.
Because federal law does not list the various species of mushrooms containing psilocybin themselves, some people arrested for criminal possession, cultivation or distribution of mushrooms have claimed innocence. Regardless, in most cases psilocybin, and psilocybin-containing mushrooms are illegal federally and statewide, with cultivation, possession and sale offenses being grounds for arrest.