Evernia Prunastri, oak moss lichen, is wildgrafted from sustainable woods in Macedonia.
 
Lichen dyes do not need a mordant.
For yellows;
Dye at minimum 50% WOF
Simmer moss for 3 hours. 
Strain through Cloth.
Add wet wool to the dye pot.
Let it simmer for 1h, cool and leave overnight.
Rinse and dry.
 
For purples extract for several weeks in a dark place in an amonia solution.
Oak moss is used often in perfumes.