This thread is more specifically about Psilocybin, but some of the things I'm going to cover apply to all psychedelic trips. Furthermore if you are interested in Psychedelics, Psilocybin is where it's at; Lsd & Company can suck it.
There are different types of psychedelic mushrooms, but the more common ones (the ones I've done), are known as Cubensis. This is what they look like dried.
Unless you absolutely know how to identify these things you shouldn't be taking anything, some species of mushrooms are very poisonous and you don't want to pick the wrong one's. A couple characteristics that help identify the Cubensis (pictured above), is the gold-ish cap color, and more importantly, if you press on the stem with your nail and bruise it a little bit, it should turn blue due to the oxidation of psilocin, & if you look at the picture above you can see what I'm talking about. They can be grown in a vacuumed glass container if you have spores, & in nature they're most commonly found on cow-pies, usually after it rains.
Set & setting is the most important factor, and this is usually where people mess up concerning psychedelics. A rave, house party, concert, or really anywhere that's going to have a large concentration of people & stimulus is generally not a good idea. I opine that these are not recreational drugs, they are spiritual tools. The best way to do it is at your house on a day you're absolutely void of responsibility, during the day time, preferably outside (I get slightly claustrophobic on psychedelics for whatever reason), with a sober sitter that can check on you from time to time. The whole trip lasts maybe 4 hours, I'd recommend just getting a stereo and hanging out on the patio, put together a playlist of songs with some positive vibes (I chose Bob Marley), and just hang out and smoke a couple joints or cigs, or a cigar, or whatever you're into.
The dosage is very important, so make sure you own a digital scale. For beginners I'd recommend about 1 gram of dried psilocybin, just to get your feet wet. Anywhere from 2.5 to 3.5 grams is what most people would consider a normal dose. 5 grams is for veterans only, and anything beyond 5+ dried grams is a Herculean like dose, and is reserved only for the bravest of souls.
As far as the experience itself goes, I can only speak from my experience, but it sort of took me through a forced examination of conscience. Whatever insecurities or neuroses which may have been bugging me were presented to me in a different light, like for example I ultimately have a fear of death, so I pondered that for some time. This all happened in the first hour or so of the trip, after it got bored of pointing out all the things that were nagging at me the trip really turned around and for the next 3-4 hours a deep calm pervaded over my whole being, a calm unlike anything I think I've ever felt. With that calm also came a genuine sense of extreme joy/happiness, & for whatever reason it was very reminiscent of almost being like a child again. I also felt a sense of supreme understanding, and I remembered thinking "I've got to find a way to put this into words so I can explain it", but it all gets too cacophonous because words do it no justice and any explanation I give you in words would only be a finger pointing at the moon, because words are a symbolic medium. As the saying goes, "To the experiencer, no explanation is necessary; to those that have not had the experience, no explanation is possible".
As far as the visual aspects are concerned, it varies in intensity depending on the dose. Obviously everyone has different experiences, but some common themes at lower doses are fractals, and for me I've noticed that trees seem to sway back and forth, and not just like a palm tree moving with the breeze, I mean like thick trees swaying from the base, also sometimes if I look at a field of grass it'll appear like it's waving like the ocean. I tried to find an example on google of what the clouds getting all fractal-y kinda looks like; it might be a little more or less dramatic than this, but you get the idea.
At higher doses there's a lot more variety and possibilities of hallucinations. At 2 grams or below you probably won't 'hallucinate' in the sense that you won't see anything that just isn't there, you'll just perceive what you see differently; at higher doses that might not be the case.
Wrapping up here, they take about 1 hour or so after ingestion to kick in. It's very important that you don't eat anything for at least 6 hours before taking them. If you don't take them on an empty stomach you'll more than likely have to vomit, & there's a possibility that even if you do have an empty stomach you'll vomit anyway. Don't freak out about it, it's normal and you'll feel better afterwards. If you're hungry during the trip, I'd recommend eating something light & healthy like an apple, orange, banana, etc. They also taste like absolute feet, really awful, I almost gagged. Some things you can do to make it a little more pleasant is slathering on some apple sauce or peanut butter, maybe wash it down with a little milk.
This should be common sense but obviously don't drive or operate any machinery, and again, if you don't know how to identify these things than you absolutely should not take them, because even if you get the right species, depending on how they were stored they might be moldy. If you have any doubts whatsoever, don't do it. The fact that these godly mushrooms aren't Government regulated is a tragedy, so in the meantime we have to be very careful not to poison ourselves. If at any point you find yourself freaking out, just take some deep breaths, try to relax, and remind yourself it's not permanent. Another trick I've picked up is if you feel a little anxious you can start singing, for whatever reason it really does work. It's also important to not psyche yourself out before you take them, you have to be in a calm space. If you're feeling trepidation and take them almost begrudgingly and continue to put yourself in a worried state of mind, you're already not off to a great start. Psychedelics are not for the timid, you have to be a strong minded individual.
I'd almost prefer if everyone just waited until they're legalized and regulated so we could remove the guesswork about the purity of the substance, but I don't know when that day will come, so in the future if anyone finds themselves interested I hoped you picked up a thing or two that might aide you.