Do note that it's not trivial to get into this in a cautious way. It will take some work to get Bitcoins, and it's possible you may lose some money to fraudulent sellers. However, the people I know source all their psychedelics this way, so it does work (at least for some people).
On the subject of finding people: if you're comfortable, you can invite your friends. This might not be wise if they're not comfortable with psychedelics, so tread lightly. Anecdotally, I got into all this literally just by asking people I knew, it turned out they where all willing and things have been fun ever since!
http://www.hopkinsmedicine.org/psychiatry/research/volunteer...
It has the added effect of being legal, and being done in a setting meant to give one a pleasant experience. Their psilocybin ("magic mushrooms") research is worth checking out. They found it had no lasting harmful effects in any of the volunteers, and overall seemed to have long-lasting positive effects in many people:
http://www.hopkinsmedicine.org/news/media/releases/single_do...
Succumbing to positive peer pressure is a good thing. If you're friends aren't into it, then go have fun doing what they're into. Compared to walking in the woods with your child, psychedelics are not very high on the scale of profundity.
The two best starting places are reddit.com/r/darknetmarkets and reddit.com/r/dnmavengers
Prioritize research and place limited trust in reviews, especially on-market reviews.
http://azarius.net/smartshop/magic-mushrooms/grow-kits/mushr...
( Note : You can buy it from different sources online, this is just a link, no affiliation )
Its easy and its rewarding :)
You ideally want to develop a trusted source, probably through someone you know
http://www.widespreadpanic.com/tour
Also, pretty much any large multi-day music festival with a campground, especially reggae. Suppliers are way less discreet at these kind of venues. You'd typically either get lucky and get whatever they say it is, or not and get something that has no effect; chances of something dangerous are low.
Discovered only a few years ago, it's way too new and untested. The effects are not the same as LSD, and reports of negative side effects are common.
Unfortunately they are commonly sold as LSD. Very sad and worrying.