Arrange apples and plums in a greased 8 or 9 inch pie pan.
Add oatmeal, brown sugar, butter, cinnamon and salt to a medium bowl. Rub in butter with your fingers, or use a pastry cutter, until the butter pieces are about the size of peas.
Sprinkle oatmeal mixture over fruit.
Bake in a 350 degree preheated oven for 40 minutes or until the top is brown and the fruit is bubbling.
Remove from oven. Serve warm or at room temperature.