28 enchantments and 3 wishes in thrice accursed, enchanted, bewitched January.
Today: Magical whortleberries as the 9th enchantment
In most circumstances, the red wishleberry is indistinguishable from its close relative, the common red whortleberry. However, under the light of the full moon, wishleberries are surrounded by a silvery sheen and in nights of the new moon, they emanate a poisonous greenish glow. If picked on such nights, they are potent ingredients for magical potions and elixirs.
Brewing potions with wishleberries is a difficult and risky business, though. If not done exactly right, they transform the potion into a strong hallicunogen which makes a drinker steadfastly believe the potion had its desired effect and absolutely nothing can convince them otherwise for a year and a day. Because of this, even experienced alchemists and magicians often shy back from using them.
D&D is something like a placeholder in this case.