Prepare rice according to package directions; set aside.
Combine next 6 ingredients in a small bowl; mix well.
Pour sherry in a lightly greased 10- x 6- x 2-inch baking dish; top with half of rice.
Pour one-third soup mixture over rice.
Arrange oysters and mushroom caps over soup mixture.
Sprinkle with lemon juice.
Top with remaining rice and soup mixture.
Bake at 350Â° for 45 minutes.
Garnish with parsley sprigs, if desired.