You should look into coconut halves if you get the opportunity. Plants, moss, etc can root into them, and they sink without soaking. They look a little more natural than pots.
There's a company that makes something called "cichlid stones" also. They're made for breeding cichlids, but look pretty convincing. I have a couple, and like the look. I used them for my Apistos for awhile before I set up the driftwood. If you face the opening backwards, they look real. Of course, if the fish stay inside, this may not be a good thing.