King Alfred’s fungus (alias coal fungus or cramp balls) grows on trees or dead wood. It does indeed resemble pieces of coal or, perhaps, buns which have been allowed to burn by a fugitive king.
The layers, visible in the partially eaten example above, mark phases of growth, like tree rings.
Like the horse’s hoof fungus in the previous post, cramp balls are inedible, but the dried interiors can be used as tinder.