You have a couple of choices. Most bed edging is a flat moss rock stacker. These stones are relatively flat with at least one flat face for the visible edge of your bed. They are a random shape and size on their other dimensions which gives them a unique look. Chop stone comes in a dimension such as 4”x4” or 4”x6” with random lengths. These are a more formal look and can be stacked easily. There are also a couple of manufactured wall options such as the Belgard Weston Stone or Melville Wall.