As you can see in the first pic, Peg placed a leaf inside the molded bowl. She did this by placing a large leaf on top of the sand hill (that is covered in plastic) and then slowly began adding the concrete mixture until she had built up her bowl to the desired size and thickness (see below). The leaf still inside the bowl will be removed by hand. Sometimes the leaves remove easily, others require a bit more work. Peg was working on removing the leaf from the inside of bowl when I snapped the photo.
Large leaves were then pressed into the bottom of the bowl (vein side down). The deeper the veins, the better the results. Hosta, rhubarb, hollyhock, comfrey are all great leaves to use for this project.
Here is the bottom of the bowl once the concrete dried. As you can see, the leaf impressions are very defined. Peg will now use a Dremel bit to smooth around the edges of the dish before painting. Be sure to wear protective eyewear when working with a Dremel. Dremel kits can be purchased at stores such as Home Depot or Lowes.
For those unfamiliar with a Dremel, it is pictured below.