Lichens can be boiled in water or fermented with ammonia after being torn up, then given a long soak at a low simmer for better color. Lichens collected in the summer yield better color than those collected in the winter. Spoiled mushrooms will still make good dyes. Bark and roots may also be used for dyeing though they require a long cooking time. It is more ecologically sound to use deadfalls or diseased trees when collecting inner bark or roots.
Spring is the easiest time to peel bark and the inner bark is usually more concentrated.
Collecting bark from twigs is less damaging . Remove mosses and lichens if you want a pure color. Chop bark or roots into one square inch sizes and soak for about three to four days. It will take twice the amount of nuts per dye amount needed. Dead ripe berries are best.