Heat a 5-quart Dutch oven or heavy stock pot over medium heat; add olive oil then turkey. Break up the turkey with a wooden spoon, and cook until it has lost its raw appearance, about 3-4 minutes.
Add the onion, celery, and garlic, and continue cooking, stirring frequently, until the onion mixture is translucent, about 5 minutes. Stir in the thyme and red pepper flakes, and mix well.
Add the squash and mushrooms. Reduce heat to low, and cook, stirring frequently to keep the squash from sticking, for 2 minutes.
Set the cheese rind in the pot, and pour in the chicken and beef stocks. Cover the pot tightly, and cook on low for 15 minutes, stirring 2 or 3 times, until the squash is soft.
Add the kale to the pot, and stir for 1 minute to allow the kale to wilt slightly (don't over-cook). Taste and adjust seasoning with salt (if needed) and black pepper. Serve hot with optional garnishes.
Recipe from http://www.soupchick.com/2012/02/turkey-kale-and-butternut-squash-soup-recipe.html, retrieved July 2013.