I've been starting to dye little skeins of yarn for the Icelandic sweater I am planning to knit using only lichen and mushroom dyed yarn. I started with Peltigera aphthosa (freckled pelt lichen). I collected about a cup of lichen and fermented it in ammonia for 4 months. It is important to collect lichen that has been detached from its substrate, so that you don't deplete the population. Lichens are slow growing and sensitive to being harvested. After the fermentation, I added 2 cups of the dye liquor to my dye pot, along with 10 cups of water and a half a cup of salt.I added 1oz of wool to the dye bath and brought the temperature up to 180F for 10 min.
I'm very happy with the colours and I am excited to try the Umbilicaria lichen I have fermenting. I need to wait 2 more months though!