While Peyote is the most famous mescaline containing cacti, I'm pretty sure it is illegal in the states, it is also endangered and very slow growing.

Get some San Pedro cacti seeds. San Pedro also contains mescaline and have been used in the Andes for thousands of years. They are legal and compared to Peyote, very fast growig, roughly doubling in size each year. and they can grow many feet tall. San Pedro is also less bitter than Peyote, and is reported to prouce a gentler, less physical trip with less nausea.

San Pedro is a hardy plant grwing very well indoors-Peyote tends to be more fussy, requiring higher temps to thrive.