Yes, you read that right. Apart from a very dry, out of date and out of print handbook, there are none. I couldn't understand it - lichen makes the PERFECT project for kids - it's easy to find, rarely toxic, and the perfect living example of a symbiotic relationship!
Anyway, the Natural History Musuem website came to the rescue with a great identification guide and we used wikipedia too - did you now that Ethnolichenology is the study of the relationship between lichens and people?! There's TONS of connections and usage, they're still used to die wool for Harris tweed and they were used extensively in embalming in ancient Egypt.
So we learnt lots, had fun and are forever changed - we can't go anywhere now without spotting all the lichen, and boy is there lots of it when you're looking out for it!
Here's some particularly fine example, our pet lichen here that now live in the kitchen, thriving with plenty of light.
Petal was inspired to do a series of colour studies based on lichens.