A couple of books came out in the last year that have chapters dealing with lichens.

Nature Obscura, a City's Hidden Natural World, by Kelly Bremmer. 2020.

Chapter titled "Dicotomy", p. 155

Entangled Life,How Fungi Makes Our Worlds, Changes Our Minds & Shapes Our Futures, by Merlin Sheldrake. 2020.

Chapter titled "The Intimacy of Strangers". p. 70.

And a new book on urban lichens from northeastern North America:

Urban Lichens: A Field Guide for Northeastern North America, by Jessical L. Allen and James C. Lendemer. 2021

Yale University Press. The field guide includes foliose, fruiticose and crustose lichen species.

Then there is this one by Warren Hatch, with excellent introduction and detailed photos and text on on lichens, mosses, liverworts in addition to many other organisms. Great introduction for kids to adults to the biodiversity that is mostly going unnoticed in your back yard.

In One Yard: Close to Nature, Book 2

Btw, Book 1, which focused primarily on arthropods, was called "one of the best science books of the year" by Science Books and Films and received accolades from David Attenborough.