Mix together oatmeal, flour and brown sugar. Add nuts. Cut in butter or margarine until crumbly. In another bowl, mix strawberries and white sugar together. Grease an 20 cm square pan. Spread half the crumb mixture on bottom. Cover with strawberries. Spread remaining crumb mixture over top. Bake at 350 deg F oven for 45 minutes. Serve warm or cold with whipped cream or topping.