1. Brown chicken in hot butter in skillet over medium high heat. Turn occasionally to brown all sides. Drain fat. Put chicken in crock pot.
2. Add tomatoes, onion, garlic and pepper. Cover and cook on low for 5-6 hours.
3. Turn heat to high then add mushrooms and peas. Cook for another 30 minutes
4. Cook yellow rice per package instructions.
5. Serve chicken and sauce over rice.