Prep time: 15 min.Baking time: 35 min.Decoration time: 25 min.
Preheat the oven to 350 degrees. Butter a 9- x 9-inch cake pan and line the bottom with parchment paper, wax paper, or foil.
Prepare the cake batter according to the directions on the box. Bake for 35 minutes. Remove from the oven and cool for 10 minutes. Remove the cake from the pan and cool completely before removing the baking paper.
Frost the top and sides of the cake. Decorate the top of the cake in a mosaic pattern with M&M'S® Brand Milk or Peanut Chocolate Candies.
Reunion Party Idea: Have all the families attending the reunion bring one of these "patchwork" cakes. Then, on a big table, press all the cakes together side by side, making one big square -- a "quilt".