I've been meaning to do this for a while, but what with the need for maps now and upcoming 'powered flight' using firework rockets, I figured it was a good time to check this off the list:
Sugarcane farm! Paper galore. Located underneath the old Subway Terminal near the Community Exchange.
I even put a little firework rocket making station below the collection chests for those quick-fixes.
Oddly, mobs spawn on the dirt blocks that the canes are planted on... did not
expect that. But don't worry about them, they can't get to the collection floor (that I've seen yet