Drain yams and discard liquid. Arrange in baking dish. Pour orange juice over yams. Sprinkle liberally with brown sugar. Dot with butter. Sprinkle with marshmallows, if desired. Place orange slices on top. Bake for 30 minutes at 350 degrees or in any oven temperature (i. E., right along with the turkey) until marshmallows melt and liquid is bubbly. Serves 6.