4 Cup (64 tbs) (Leaves And Fine Stems Only, 1 Or 2 Bunches, Depending On Size)
Combine the mushroom slices, parsley, and chives in a small bowl.
Blend together the oil, lemon juice, mustard, pepper, and salt and add to the mushrooms.
Toss well together.
Cover and refrigerate for 15 minutes.
Put the watercress in a large salad bowl, add the mushrooms and dressing, and toss to coat all the leaves.