"The first time I had this cake was in the 1st grade when I was learning nursery rhymes. My teacher called it Mary Mary Quite Contrary's Garden. It must be enjoyable for both kids and adults, as I still remember it 16 years later! I've seen 3 other variations of this, but I felt that they needed more substance. This version has layers of chocolate cake to make it almost like a trifle. Add an artificial plant for decoration and serve with a small shovel."
Preheat oven to 350 degrees F (175 degrees C). Grease two 9-inch round cake pans with cooking spray.
Combine chocolate cake mix, water, eggs, and vegetable oil in a large bowl; beat with an electric mixer until moistened, about 30 seconds. Increase speed to medium and beat batter until smooth, about 2 minutes. Divide batter between the prepared pans.
Bake in the preheated oven until a toothpick inserted into the center comes out clean, 24 to 29 minutes. Cool on a wire rack for 15 minutes. Invert onto the wire rack; cool completely, about 15 minutes. Slice 1 cake into 1/4-inch layers. Reserve second cake for another use.
Pulse chocolate sandwich cookies in a food processor in batches until finely ground.
Combine cream cheese, vanilla pudding mix, and chocolate pudding mix in a large bowl; beat with an electric mixer until smooth. Beat in milk until evenly blended. Fold in whipped topping with a rubber spatula.
Pour some of the cookie crumbs into the bottom of a 9-inch trifle bowl. Top with a layer of pudding, 1 layer of chocolate cake, and some gummy worms. Repeat layers twice more, ending with remaining cookie crumbs on top.