Psylocibin is the main active ingredient of "magic mushrooms" (Psylocibe sp., here known as mongis or bongis). It was confirmed in 2008 as the "best trip" by quality rating of the experience in all aspects.
Now it seems it is also the magic herb that can calm people affected by anxiety, at least in advanced cancer patients. Sadly, because of socio-cultural prejudices, the research on the hopeful effects of psychedelic drugs was halted in the 1970s under a heavy load of repressive laws.
Read more at Science Daily.
Ref. Charles S. Grob et al., Pilot Study of Psilocybin Treatment for Anxiety in Patients With Advanced-Stage Cancer. Arch Gen Psychiatry, 2010. Pay per view.