I had another thought. I failed to mention that you can also collect mature mushroom caps, place them on a piece of white paper and let them dry. They will shed their spores (called a spore print by people who use this as one means of identifying mushrooms) and simply brush some of the spores into your tank and see what happens. You may even be able to purchase some of the exotic mushroom spores on line-- I haven't checked this out.
They will start out with a mycelium, which looks like a sprawling fungus. The mushrooms are the "blooming" or reproductive organ that may come later.
As for other unusual plants, you could try some of the smaller carnivorous plants, but avoid Venus Fly trap, as it doesn't survive for long in a tropical vivarium. I have a neat Spiranthes that captures a few left-over fruit flies in the P. terribilis tank, and want to try some of the Nepenthes at a future date. From what the carnivorous plant enthusiasts have told me, they are perfectly safe for frogs. Non-the-less, I'm going to only try them with the larger species, not my precious tiny ones. The Adiantum ferns are delicate and feathery if you plant them somewhat above the wet portions of the tank. Try to stick to relatively miniature ferns, as some will really take over. I also use some cacti-- Rhipsalis sp. in particular, which are interesting epiphytic jungle cacti These are usually spineless, although they do have some recessed bristles in the areoles. They add something different among the bromeliads. You can look them up on the internet. There is a specialist who grows all kinds of them, but I can't remember his name right now. I found him by simply entering Rhipsalis on the search.
You could also check out my photos of some of the plants in the gallery under cages and terrariums. It's not a complete gallery of what I use, but may give you some ideas. I haven't added others because I've been too lazy to upload them, and no one seemed particularly interested.
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Patty
Pahsimeroi, Idaho
4 D. auratus blue
5 D. galactonotus pumpkin orange splash back
5 D. imitator
6 D. leucomelas
4 D. pumilio Bastimentos
4 D. fantasticus
4 P. terribilis
4 D. reticulatus
4 D. castaneoticus