Cook scallops in the same pot with the bacon grease for about 3 minutes, stirring once halfway through cooking time until scallops are cooked and opaque through the center. Remove scallops and set aside.
Add mushrooms, celery, and onion to the same pot. Cook until onions are translucent.
Add remaining ingredients (except for the bacon and cooking Sherry).
Bring to boil. Let simmer for 30 minutes. Using an immersian blender, blend just enough to make the broth a little creamy, but still leaving the soup chunky.
Add scallops and cooking Sherry. Continue to cook until scallops are heated through.
Spoon chowder into bowls. Garnish with bacon and additional thyme leaves.