Cooking with Ornamental Cabbage (Kale)?
Ornamental cabbage is often actually a kale.

See this link with pictures very similar to yours:
http://www.arhomeandgarden.org/plantoftheweek/articles/ornamental_kale.htm

Kale is edible and nutritious but it is tough and very strongly flavored compared to cabbage.

Kale recipes usually involve long braises in flavorful liquid to break down the toughness. Cabbage recipes, which require less cooking lest you release the dreaded sulfur demons, would almost certainly not be sufficient.