Mosses

I've never heard of anyone trying to grow moss indoors, would think it unlikely as they like cool damp places. Pearl wort is not a moss but an invasive weed, well so is moss in my view, see http://www.dgsgardening.btinternet.co.uk/pearlwort.htm. I doubt you will find one to buy anywhere

pearlwort dies back in the autumn too. it self seeds in areas of my garden [sadly]
moss will survive but you need to keep it moist as i doesnt have a root system. it is a very primitive plant form really.
what ever you do please dont take moss plants from the wild. they are very important in the environment.

I just want to second what Seaburngirl said about not taking moss from the wild - this will have a damaging effect on the environment.

Maybe I can buy Irish moss seeds and plant it in a terrarium???