Step 1Bring 2 cups of salted water to boil in a saucepan. Add the rice and simmer, covered, until the rice is tender but still has some bite to it, 35 to 40 minutes. It will not absorb all the water. Drain.
Step 2Meanwhile, melt the butter in a skillet over low heat. Add the flour and blend well. Cook, stirring, until light golden, 8 to 10 minutes. Be careful it doesn't brown.
Step 3Heat 6 cups of the chicken stock to a simmer in a large saucepan. Whisk in the flour mixture until smooth. Strain the mixture.
Step 4Wipe the pan clean and heat over medium-high heat. Add the bacon and cook until almost crisp, 5 to 6 minutes. Stir in the onion, carrots, celery and mushrooms. Cook until tender, stirring occasionally, 10 minutes. Stir in the pimentos, bay leaf and thyme. Season to taste with salt and pepper.
Step 5Add the stock mixture and wild rice to the pot. Simmer over medium-low heat, 20 to 30 minutes, adding more stock if the soup becomes dry. Stir in the half-and-half and heat to serving temperature. The soup will be thick. Adjust the salt and pepper to taste. Remove the bay leaf before serving.