Fantasy Novel about a figure like Robin Hood, but includes characters that are magical. One of the human characters has a way to talk to the wee folk or elves. Read in 1990s. Spoilers ahead.

[Eric]

Read in the 1990's but feel like it was an older sold green cloth cover like books from 1950's to 1970's. Can't recall if the character was Robin Hood or another prominent figure like King Arthur, but blended the two elements well. (view spoiler)[ The supporting character who was a close friend of the main character could talk to the prince of wee folk, and they would help him. This was in part because he was, unkowingly, the son of this prince of the elves. (hide spoiler)]