Typically termed as a gateway drug into other more serious drugs, such as heroin, cocaine, PCP, LCD, and others, psilocybin mushrooms are used for its effects as a hallucinogen. Drug rehab centers often provide information about this kind of drug as a result of its reputation. Among these effects is a changed perception in reality (otherwise known as tripping), relaxation, distortions in what the person is seeing, and a detachment from their physical body. Other experiences are color and light collections vivid in color and form and fantastic and strange visions.
As far as symptoms go, there might be shivering, numbed tongue, perception alteration of time, sweating, a light head, and in more extreme cases anxiety. Because it acts as a hallucinogenic, law enforcement often blame it for leading people to other hallucinogenic like PCP and LSD. A residential drug treatment center will usually have more information about why some people consider it a dangerous drug in its capacity to lead to other more serious drugs.
Other reasons for avoiding the psilocybin mushrooms include what kind of form is taken, from the dried and wild varieties. Detrimental health problems can occur with the wrong type taken. Additionally, there are certain kinds of fungi that look similar to the psilocybin mushrooms. While causing the hallucinations associated with tripping, it can also in the most extreme cases cause death.
Because taking LSD and the psilocybin mushroom cause reactions that alike, this is another reason for its reputation as a gateway drug. LSD does gives its users a longer and more prolonged experience due to the chemicals used in making the drug. These synthetic chemicals are the reason LSD is considered a dangerous drug for people in the medical community. PCP and strychnine, a substance which is poisonous, are often found mixed into a batch of LSD. And while PCP also has a similar role to LSD and the psilocybin mushroom, it has far more dangerous effects on its uses than either of the two other drugs.
You asked whether or not Psilocybin mushrooms could be laced with LSD. LSD is most commonly used in one of two forms. It is either absorbed in its liquid form onto a piece of paper (a blotter), and chewed or taken as a pill. It may be possible to soak Psilocybin mushrooms in this liquid, or mix LSD with Psilocybin in its powdered form.
More information about the psilocybin mushroom can be found at centers for treatment for drug addiction. There is also much literature available at local libraries about the connection between the mushroom and other drugs with hallucinogenic properties.