I used a combination of cremini, porcini, and maitake (also known as hen of the woods) mushrooms for this soup, but you could use any fresh mushrooms you have on hand. 

Mushroom broth can be made using 8 oz. mushrooms, chopped; 2 carrots, chopped; 1 - 2 oz. dried mushrooms (porcini or shitake); and 6 cups of water. Saute the fresh mushrooms and carrots until browned, add water and dried mushrooms, and bring to a boil. Lower the heat to a simmer and cook for about 1 hour. Season with salt and strain.