Salvia was/is traditionally used as a hallucinogenic mushroom substitute during the dry season in South/Central America. It grows wild, but there is also a variety that researchers speculate has been cultivated for at least a Millenium.
Fresh salvia is weaker in effect than fresh mushrooms, but it is a useful substitute in rituals, ceremonies, and journeys. The wild variety is rarer, more potent, and more desirable. The cultivated variety is more common, and it's often possible to buy clones of this variety from various botanical outlets or local herbologists.
The traditional method of use is to roll up a dozen or so leaves into a cigar shape, then tuck the cigar under your lip or into your cheek, beside your gums, and let your saliva act on the roll for 15-20 minutes.
These days you can buy a salvia extract, which is popular with weekend psychonauts. I personally recommend avoiding any refined substances, however. If the use of salvia is required, try to find a raw source (as is the case with any herb.)
CSP
"It is the peculiar quality of a fool to perceive the faults of others and to forget his own." -Cicero