Melt four tablespoons of the butter in a large, heavy pot over medium heat. Add the onions and sauté until tender and caramelized, about 25 minutes. Transfer to large bowl.
Melt remaining four tablespoons of butter in same pot over medium-high heat. Add the mushrooms, one tablespoon of the thyme, and the minced garlic. Sauté until the mushrooms are deep brown. Add to bowl with the onions.
Bring broth, one tablespoon of the thyme, and two teaspoons of the sage to boil in deep, heavy saucepan.
Mix in the wild rice and return to a boil. Reduce the heat, cover, and simmer 30 minutes. Mix in Carolina Gold rice, cover, and simmer until all rice is tender and almost all liquid is absorbed, about 20 minutes. Stir in the caramelized onions and mushrooms, the remaining tablespoon of thyme, and the remaining teaspoon of sage. Stir in cranberries. Preheat oven to 350ºF.
Cover and simmer five minutes, stirring often. Stir in 3/4 cup of the parsley. Transfer stuffing into buttered 13 x 9 x 2-inch baking dish. Cover with buttered foil, buttered side down. Bake until heated through, about 30 minutes. Uncover and bake a few minutes longer, until top is slightly crisp and golden. Sprinkle with remaining parsley.