I love learning old English words for things in nature.
'Beam' is the saxon word for tree, as in 'hornbeam', 'whitebeam', also used to describe supporting timbers in buildings.
The best names are those which describe a use or characteristic - such as 'razor strop' for the bracket fungus which grows on birch trees. People once used it, when hard and dry, to sharpen knives and other cutting blades.
The 'penny bun' fungus looks exactly like it's name, but the description does capture the gourmet properties of this highly sought mushroom. And 'King Alfred's cakes' which grow on dead wood are like burnt lumps of charcoal. They make great firelighters too when they're dry.
Let me know your favourites...