Stuff plugs of green moss into a 1-gallon plastic bag. Add 2 cups of water to the bag and then seal the bag shut, securely. Let the moss absorb the water for a minute or two.
Poke holes in the bag with a sharp knife or skewer over your kitchen sink. Use the rolling pin to expel all of the excess moisture in the bag.
Mold the moistened moss with your hands to form a domed shape that is flattened on the underside.This gives it the shape of a snow globe. Place the domed moss form on a paper towel. Let it dry in this form for 24 hours. The end result will be a dome-shaped, dried green moss pillow. It should shrink as it dries, but shouldn't be smaller than 5 inches across and 3 inches tall.
Snip two lengths of hemp cord, each measuring 8 inches long. Tie one of the cords vertically around the middle of the moss pillow. Secure it with one tie and no bow. Tie the second cord horizontally around the center of the moss pillow, overlapping the first cord. Secure this one with a single tie. Grasp all four ends of the two cords, separating them so that you hold two ends in each hand. Tie these ends into a simple bow.
Add your own finishing touches to the moss pillow. For instance, insert small river rocks into the plush surface of the moss for a speckled look, or arrange the moss pillow on on your mantel with a flameless display candle inserted into it.