In a large heavy pot, melt butter over medium to medium high heat. Add the onion, celery, carrots, mushrooms, and garlic. Stir well and sauté until onion is transparent and softened. Blend in flour, cooking until it bubbles a bit. Gradually add the broth, stirring constantly. Turn up the heat a bit and bring the soup to a low boil. Boil for 1 minute.

Reduce heat slightly and add half and half, salt, black pepper, bay leaf, thyme, rosemary, peas, potatoes, and smoked turkey. Simmer for 35 to 40 minutes, or until potatoes are tender to your liking and the soup is thoroughly warmed. Stir in lemon juice. Taste test to see if soup needs more salt and pepper. Serve with warm biscuits.