The spores of these mushrooms are not considered ‘possessing of an illegal substance’ because they do no have psilocybin. However, this isn’t true in all states. In California, Idaho and Georgia, they are illegal. 

In New Mexico, individuals can grow personal batches of psilocybin mushrooms without it being deemed as manufacturing a controlled substance. Whether or not this means that they can be used or possessed legally is another story and warrants further study by those interested in using them in the state of New Mexico.

http://www.erowid.org/plants/mushrooms/mushrooms_law.shtml