I've seen versions of these that look more like skillets but have never seen one with a cover before.
I like Lawrence's idea for mushrooms a la escargot. I like snails, but I like mushrooms more and they're less work.
When I was a waiter in a formal restaurant, we served escargot two ways; in the shell or on mushroom caps. The latter was much easier to enjoy without any labor involved, and provided the best of both worlds.
Be sure to serve with some good French bread to soak up the butter sauce.