Tolkien uses nine “forest-” compound words, of which three are attested in OED – forest-floor, forest-path, and forest-road.

OED has  61 “forest-” compound words, by the way:

forest-bred
forest-brother
forest-brown
forest-clad
forest-court
forest-craft
forest-crowned
forest-deep
forest-dove
forest-dweller
forest-dwelling
forest-feller
forest-felling
forest fire
forest-floor
forest-fly
forest-folk
forest-frowning
forest-fruit
forest-glade
forest-green
forest-hearse
forest-house
forest-kangaroo
forest-land
forest-lawn
forest-laws
forest-leaf
forest-life
forest-like
forest-lodge
forest-lord
forest marble
forest-matter
forest-nymph
forest-oak
forest-path
forest pathology
forest-peat
forest-pony
forest red gum
forest reserve
forest-ridge
forest-rights
forest-road
forest-rustling
forest-school
forest-shade
forest-sheriff
forest shrew
forest-side
forest-skirt
forest-sport
forest-steading
forest-stone
forest stream
forest-top
forest-tree
forest-walk
forest-wards
forest-wood

“forest, n.” OED Online, Oxford University Press, June 2017, http://www.oed.com/view/Entry/73187. Accessed 13 September 2017.