Perhaps Tolkien's only foray into outright comedy, Farmer Giles of Ham is humorous on multiple levels, from its nature as a parody to the many language-based jokes Tolkien includes in the story.  It's a short, whimsical read very different from what most of us know Tolkien for, and well worth picking up.  I recommend picking up this compilation: https://www.amazon.com/Tales-Perilous-Realm-J-R-R-Tolkien/dp/0547154119/ref=sr_1_4?s=books&ie=UTF8&qid=1477875238&sr=1-4&keywords=farmer+giles+of+ham  Unfortunately I can't seem to find an edition with commentary to explain the jokes that require more learning, but this at least has several other stories worth having in your collection.