With only the last sixth of my lichen dye stock remaining, I once again reviewed my books on natural dyeing and found no answers. But with one more web search, I found a blog:
The author has successfully dyed several types of lichen, with resulting color like this:
My color looks like this:
You can see its ancestor lichen to the left of the branch.
From the instructions on the mycopigments blog, I've discovered that I was supposed to expose the dyebath to oxygen every day to intensify the color. I'm happy with the pastel color, though.
Next time I gather lichen I'll try again.