You can take verses from songs and poems in the books that are elvish. Like the Elbereth Gilthoniel, silivren penna miriel one, or Galadriel's lament. If you want to actually learn elvish, you could try the Languages forum. They might have something there.
And... oh... *digging through her website memory banks* I know there's a Sindarin dictionary that I found that has a lot of words...
Aha!
Hereit is!!