Is there one? I've been looking and I can't find anything. And I foresee my campaign going there, soon. I've looked in the manual of planes, I couldn't find anything there (unless I manages to miss it entirely , which I haven't completely ruled out).
I don't particularly mine what version it's for, I can adapt.
Please help. Thanks in advance 
There is a few books for it in the 4e era, but before that the feywild I actually think is only barely mentioned, if it existed. Im not really sure to be honest. Though there is a good amount of stuff in the 4e book is going to power list and other mechanics of 4e (just the way the edition works) there will be content in there you can use as well. Look at Celtic myths, as they are filled to the brim with Fey and feaire creatures, bursting with it really.
I believe what you want is Heroes of the Feywild. It's a 4e book, so most of the crunch won't be of any use if you're playing another edition, but there's plenty of fluff too.
Not quite the same thing (unless you want to view it as a Demi-Plane that grew into the Feywild) but Basic D&D had the Sylvan Realm which the party might visit via the Tree of Life scenario.
The Feywild was part of a number of DnD online articles. Unfortunately my index of everything in the Feywild was lost when they changed the wiki format. Heroes of the Feywild and 4E Manual of the Planes is your best bet for the most stuff. Also the 4E Underdark book contained some info on the Feydark home of the Fomorians and Gnomes. If you have a DnD insider subscription, well that's weird to have still . . . but you can check out these articles
the Prince of Frost: http://archive.wizards.com/DnD/Article.aspx?x=dnd/drfe/20090424
the Satyrs of Night: http://archive.wizards.com/dnd/Article.aspx?x=dnd/dufe/20111216
Hyrsam: http://archive.wizards.com/DnD/TOC.aspx?x=dnd/4new/drtoc/422
Bramble Queen: http://archive.wizards.com/dnd/Article.aspx?x=dnd/dufe/20101207