The seeds of several varieties of MorningGlory (Ipomoea violacea) contain a naturally occurring tryptamine called LysergicAcid Amide (LSA), which is closely related to LSD. Seeds are taken orally, and can be eaten whole or the active alkaloids can be extracted.
The most common active varieties of seeds are Heavenly Blue, Pearly Gates, and Flying Saucers. Like LSD, LSA acts as a "psychedelic" or "hallucinogen" which can have strong mental effects.
I didn't have any LSD so I orally ingested some Morning Glory seeds instead.