Grease or spray a 9 x 13" metal pan and fill the bottom completely with miniature marshmallows. Prepare white cake mix according to directions on package; add the 1/3 cup sugar, and spread on top of marshmallows. Thaw two cartons frozen strawberries and mix with strawberry jello; spoon onto top of cake. Bake at 350 degrees for 45 minutes. The strawberries will sink down and melt with the marshmallows. Cut slices and serve upside down. This is a great cake for Valentine's Day and summer events!