Yarns dyed with pigments derived from mushrooms and lichens

Information about these natural dyes at the Cornell Mushroom Blog.  Image via.

Tyrian purple, the desired color, was originally extracted from a marine mollusk, and initially, lichen dyes were used only as underdyes. However, as the mollusk population was depleted, lichens became the primary source of the valuable purples, for they also were found to have a natural affinity to woolen and silk textiles...

The techniques and knowledge for making orchil lichen dyes were great secrets in early times. The earliest known description of the preparation of orchil was given by Roseto in 1540. The process generally consisted of obtaining the desired lichen, adding it to stale urine and slaked lime, and waiting...

I also found this re the history of purple dyes.