The Strange and Magical Potato

The potato lives in a “very poisonous family indeed...addictive tobacco, deadly nightshade, hallucinatory henbane, hypnotic mandrake and delirium inducing datura.” Its own poison, Solanine, can cause nightmares, hallucinations & paralysis so it seems ripe for folklore and magic.
Old Mother Redcap, witch of the Essex marshes, might be known for taking time out from crossing rivers on hurdles to sit at her kitchen in the haunted Devil’s House peeling potatoes and singing 'Holly holly, Brolly brolly, Redcap! Bonny bonny,’ but she might have just been making lunch.
There have also been lovely children’s parades where they dance with potato sacks held high, followed by the inevitable sacrifice, with either the blood of a young and flawless llama poured over the spuds or the blood of a young girl who had been painted, roasted and shot with arrows.
At harvest and planting, toads in the potato field can indicate the crops luck. A sprig of cypress was planted with the crops in Ireland and burnt with the harvest, and in Northern Scotland all the family would have to taste newly dug potatoes otherwise “the spirits take offense and the potatoes would not keep.” In parts of Northern Europe the last plant pulled catches the Potato-Wolf or Dog. A mythical beast akin to the Pea Wolf, the Oat Goat and the Hay Poodle who roam the crops and are cut down in the harvest. The harvester of the last plant (in some areas called the Old Potato Woman) takes on attributes of the wolf, biting and howling because “She has the Wolf.”
A popular Victorian belief that a potato carried around in the pocket would cure rheumatism, often with the caveat that it must be stolen (or begged). But the magical protection of a shriveling spud covers more than rheumatism. A pecked potato in your pocket stops toothache and as well as the following list of pocket potato cures: back pain, cramp, chills, gallstones, piles, neuritis and nosebleeds. Whereas stuck under the bed it aids conception and stops night sweats. Not to count the endless remedies that have been applied or swallowed in desperation that are made from potato (raw, sliced, tied to your head or boiled in a sock), potato peel or potato water.
And on the malevolent side there are potato poppets—put your enemy’s fingernails or spit in the potato and hang it in smoke to dry up. Your enemy will shrivel just like the potato.