To make stuffing: In a small bowl, soak the porcini mushrooms in one cup of water for 25 minutes. Strain mushrooms and liquid through a coffee filter placed in a strainer over a bowl. Reserve liquid (about 2/3 cup). Rinse and chop mushrooms; set aside.
In a large sauté pan over medium heat, melt 3 tablespoons of the butter. When butter is foamy, add onions, celery and fresh and reserved mushrooms. Stir until onions are soft and translucent, about 8 minutes. Add rice, herbs, salt and pepper. Moisten slightly with about 3 tablespoons reserved mushroom water, depending on dryness. Makes 41/2 cups stuffing.
Melt the remaining butter and set aside. Gently fill bird cavities with stuffing. Fold excess skin over opening and tie legs together. Place hens, with ample space between them, on two 12" x 19" baking sheets. Brush hens generously with butter. Bake about 1 hour.