In a large skillet with a high rim, cook bacon on medium-high heat. Remove the bacon, leaving the rendered fat in the pan. Stir in the celery, green onions and Vidalia onions, potatoes and corn. Add the thyme, bay leaves, 1/2 teaspoon salt and a few grinds of pepper and cook, stirring, 3 minutes. Stir in the flour until incorporated, about 2 minutes. Stir in the milk, then cover and bring to a boil. Uncover, reduce the heat to medium low and gently simmer until the vegetables are tender, about 6 minutes. Discard the thyme sprigs and bay leaves.
Season the shrimp with Old Bay. Stir in the shrimp and cook until opaque, about 4 minutes. Season with salt. Divide among bowls and sprinkle with green onion and chopped bacon.