An article, with recipe, for creating moss patterns where you have moist shade. An old wall, a low-lying spot, anywhere near a drain will work well.
Here's another recipe...
Several clumps of moss
1 container yoghurt or 12 oz buttermilk
1/2 tsp sugar
Put all in a blender, blend. Transfer to a jar and paint onto your surface with a brush. Make sure to mist the area frequently after applying the mixture until it's established. You can also create your pattern indoors on a seed tray containing compost or on the form you'll be using outdoors. Transfer to the outdoors when the moss has established, and continue to mist until it's well-situated.
A great project with kids!
And related fun in very small spaces (click on Secret Worlds).