From a 1967 article in TIME:
Current smokes include almost anything from the supermarket spice and herb shelves plus dried hydrangea leaves, chlorine-soaked lettuce, and green peppers (aged until rotten, then used as a bulbous cigarette filter). But far and away the biggest new fad is tripping on banana peels.
Delicious Legality. The kick is known to hippies as “electrical bananas” or “mellow yellow.”* Banana-heads scrape the white fibers from the inside of the peels, boil the scrapings into a paste, which is then baked. The dark brown ash that results is smoked in hand-rolled cigarette “joints” or in pipes, tastes vaguely like a burning compost heap.
Most people who have tried mellow yellow do not try it again. The reason is simple: lots of work for little, if any, high. But banana-heads find the craze appealing, largely because of its delicious legality.
But do bananas really work? The best that chemists can suggest is that bananas contain serotonin, a neurochemical that is closely related to such potent mind-benders as psilocybin and dimethyl tryptamine, and which just might, under combustion, trigger genuine physiological effects. It is far more likely that any high produced by bananas is imaginary, another indication that, given a receptive state of mind, it is possible to turn on with practically anything—or virtually nothing.
* From British Folk-Rock Singer Donovan’s Mellow Yellow: “Electrical banana is gonna be a sudden craze. Electrical banana is bound to be the very next phase. They call it mellow yellow (quite rightly) . . .” Donovan insists that his song has no hidden meaning, but seekers found one anyway.
read entire article here.