These are easy to make, just get some old garden poles and cut them into short stakes. Plane off a smooth spot for the text, then use your soldering iron with burning tip to burn in the marker text.
Adam, no engraver was used, just the soldering tip. The pine is actually difficult to work with since the light wood burns easily but the dark wood doesn't want to burn so well. So you have to use light pressure on the light wood and harder pressure and multiple passes on the dark wood.