When I was in high school, I was obsessed with water gardening.  My father and I built a little concrete pond in the backyard and I stocked it with plants and aquatic life.  But the places where the concrete liner rose above the surface were an eyesore, so I did everything I could think of to try to get moss to grow there.  I had absolutely no luck.  In the end, I decided that moss was hard to grow.

Looks like my raised beds don't think so.  After our six months of autumn, one bed has grown quite a nice crop of moss amid the Egyptian onions.  I hope that means that my no-till technique has built an equally lush soil ecosystem below the surface!