Add beef to Dutch oven; cook 7 to 9 minutes, stirring frequently, until thoroughly cooked. Add reserved mushrooms, chopped onions, carrot and garlic; continue to cook 4 to 6 minutes, stirring occasionally, until softened. Sprinkle flour, thyme, salt and pepper over beef and vegetables; cook and stir 2 minutes. Stir in broth; heat to boiling. Add barley; reduce heat to medium-low. Simmer 35 to 40 minutes or until barley is cooked. Stir in whipping cream; cook 1 to 2 minutes or until hot.