From what I can make out, you have a few java ferns, a marimo ball and maybe a sword in the back. I can't tell from the picture, but the java fern should be attached to a rock or driftwood. If you bury it, the rhizome will turn into mush and eventually kill the plant (I've always attached, so I can't speak to the reality of this)
Adding some of those smooth round stones (blue white and red.. patriotic huh? but that's the colors they usually come in) I think would look nice in this tank.