1. Peel shrimp; devein, if desired. Snap off and discard tough ends of asparagus. Cut asparagus into 1-inch pieces.
2. Bring chicken broth to a boil in a medium saucepan over medium-high heat; whisk in grits and half-and-half. Cook, whisking constantly, 7 minutes or until thickened. Remove from heat. Stir in 2 Tbsp. butter. Keep warm.
3. Melt remaining 2 Tbsp. butter in a large skillet over medium-high heat. Add asparagus, mushrooms, green onions, and thyme, and sauté 3 to 4 minutes. Add shrimp, and cook 2 to 3 minutes. Stir in salt; cook 3 minutes or just until shrimp turn pink. Serve immediately over warm grits.