MAKE THE DRESSING
Butter a deep 9-by-13-inch casserole. In a large skillet, melt the butter. Add the celery, garlic, onion and thyme and cook over moderate heat, stirring frequently, until the celery is softened, 8 minutes. Discard the thyme sprig. In a large bowl, break the corn bread into 1-inch pieces. Stir in the celery mixture, the oysters and their liquor, the broth, lemon zest, lemon juice and parsley. Season with salt and pepper; mix in the eggs. Spread the dressing in the casserole. Cover with foil and bake for 40 minutes; uncover and bake for 25 minutes longer, or until the top is lightly browned.