How to make "edible dirt"

Merlin and Rebecca have a recipe for making Potted Potatoes in Edible Dirt. Everything in the flowerpot is edible. Next, they should make an edible flowerpot to go along with it.

It's a little odd to look at items in a market and gauge how much they look like dirt, but that's just what we did. Pumpernickel bread and dried chanterelles were obvious winners. Roasted pumpkin seeds were added in for flavor, a punctuation of salt and fat. The bits of mushroom provided that dirty, earthy taste all soil should have (right?) and, visually, it reminded us of crumbled dry leaves settling into the earth before the winter frost. Food dirt shouldn't just be edible, but also enjoyable.