A thin pale crust (2nd photo shows the overall colour better). Some pale buff/orange apothecia. On hawthorn twig. Pinhead is 3mm dia.
Caution: Do NOT use iSpot to identify fungi to eat!
Some fungi are very poisonous so a mistaken ID could have serious consequences.
No interactions present.
I think it could be, but the spores need to be looked at even to be sure it is a Lecania - then, if the right dimensions, then yes. But my experience with Lecania spp. is that they are an essential microscope job.
Unfortunately I don't have access to a microscope at the moment. The (same!) twig is still on my desk so I'll hang on to it and try to get hold of a microscope.
Lat/Lng: 55.4733, -3.2004
OS grid ref: NT242205