Place egg whites in mixing bowl and whisk lightly.
Add 1 tablespoon of herbs to egg mixture and blend in well.
Coat a small skillet with non-stick cooking spray and set it over low heat. Pour egg in mixture and slices mushrooms. When eggs begin to set, left edges with spatula and tilt skillet to let uncooked egg run to the bottom; sprinkle parmesan cheese over omelet.
Continue cooking omelet over low heat until set. Fold the omelet over into a half circle and cook until fluffy.