1. Cannabinoids (marijuana, hash)
2. Cocaine (cocaine, crack, benzoylecognine)
3. Amphetamines (amphetamines, methamphetamines, speed)
4. Opiates (heroin, opium, codeine, morphine)
5. Phencyclidine (PCP)

It is, however, technically possible to detect psilocybin and psilocin with a drug test. Because they are less standard, these tests are more expensive to give than the basic test. The more expensive and comprehensive drug tests are sometimes used in cases where there is specific reason to believe that psilocybin mushrooms use is an issue; for example, an individual who is on probation for mushroom use might be specifically tested for the presence of psilocybin in hir system. However, generally mushroom use will not cause an individual to test positive on a random drug test given by an employer or school, or by the legal system.

Once ingested, most of the psilocybin is converted into psilocin within the first hour. Most of the psilocin is then excreted within the first 8 hours...but portions remain in the system for several weeks. From Stafford's Psychedelics Encyclopedia:

"High dose studies of rats suggest that psilocin taken orally is distributed througout the body. Concentrations in tissues appear highest about half an hour after ingestion, decreasing rapidly over the next three to four hours. The adrenal glands of the test animals show the highest concentrations after the first hour, until then the kidneys have more. The small intestine, skin, bone marrow, lungs, stomach, and salivary glands also have significant concentrations-- greater, in fact, than those in the brain...

In the high dose study of rats, all but 6 pecent of the psilocybin was excreted within twenty-four hours. In humans, only 80-85% of psilocybin and its metabolites is excerted within 8 hours, in the urine (about 65%), bile and feces (15-20%). Some 15-20% olingers on, stored in fatty tissues; significant quantitites appear in urine up to a week later. A full 25% of the originally administered dose enters urine as psilocin."