Well you know that all of us here will give you all the help we can in your terrain project.
I guess you are going for this kind of a look;
Sorry for the small pic, but for a close up from the movie;
What's interesting it that your terrain doesn't really have to mirror the movie. IIRC, Tolkien either served in WWI or knew men who did, and his idea of the dead marshes was based on scenes like this from the battlefield;
So a fairly simple board idea with lots of chewed up ground (spackle or equivelent with brown flock), marshy type grass (I think GF9 has some good looking stuff), dead trees (old twigs and dried out hedge roots), and standing murky water (any of various water effects).
For cheap dark brown ground flock, I saw a tip on another site when a guy saved his old tea bags, dried them out, and used the old tea leaves for ground cover. I'm trying it out now, will let you know how it works!
Good luck at the Vegas GT! That will be an incredible event if past years are any indication. Nice to know someone who is actually going!