Indigo Milk Cap (Lactarius indigo): The Lactarius indigo mushroom gets its name "Indigo Milk" from the blue milky liquid it exudes when cut with a knife. This bizarre mushroom grows in North and Central America and is usually characterized by its silvery-blue coloring. Although, as this bizarre mushroom ages, its coloring changes to a grayer, greenish-blue. Indigo Milk Caps grow either scattered or in groups, on soil or oakwood or pine. They're most commonly found from July through October, and like many other fungi on this list, they have a symbiotic relationship with the trees from which they often sprout. Their preferred trees tend to be oak or pine. Because of this bizarre mushroom's vibrant pigments, it's also been known to be used as a dye for textiles.