The Hobbit

[Birdland]

"Tell me what you want done, and I will try it, if I have to walk from here to the East of East and fight the wild Were-worms in the Last Desert."
Bilbo Baggins,
in The Hobbit, An Unexpected Party

Of course, that was a Were-worm, and not a real worm, so I guess the jury's still out on whether there were Dragons in the East.