(belongs in psychedelics forum)...
peyote grows in southwestern united states and in northern mexico(not south america)...
south american cacti containing mescaline are pretty much in genus Trichocereus...
in USA, only member of native american church (NAC) are legally permitted to use peyote (and some states and even the feds (supreme court) are still sorta being assholes about it (court rulling against religioous use, so the congress has to pass relgious freedom restoration act for NAC members; local authorities confiscating live plants; people (NAC members) losing their jobs for testing positive for mescaline after a peyote ceremony; & crap like that)...
also, due to improper harvest methods by people who don't know what they are about (mostly "white-eyes"), peyote in the wild is close to extinction...
peyote seeds and plants can be purchased in most countries other than ussa & mexico...
trichocereus seeds and plants can be legally purchased pretty much anywhere, and are not close to ectinction, are quite rapidly growing cacti, and have a fair amount of mescaline (varies considerably---but a kilogram of fresh cactus might contain up to a gram or so of mesc...)
of course in the ussa, extracting the chem, or even brewing up a tea for chugging or a tarry goo for encapsulating would be illegal... but just growing them to look at (or as a spiky hedge along your property line) would be OK...
ummmm if you do a google search (keywords: peyote, san pedro, mscaline cacti, lophophora, trichocereus...) you will find all sorts of interesting info and organizations on the web...