Moss

I want to build a bed using masses of bulbs, of various varities. However mud is not nice to look at, what is best to use when covering a bed you don't want mud being shown?

I was thinking moss, but was worried it would damage the bulbs?

Or grass, but this would need to be short growing grass if that is even possible. I like the look of moss when if grows in pots on its own, but how easy is it to buy and grow?

Help 

Chris