Preheat the oven to 350 degrees. Spray a 9-by-12-inch baking pan with cooking spray.
Whisk together the eggs, oil, and water. Add the cake mix and whisk until fully combined. Whisk in the vanilla. Pour the batter into the prepared baking pan and bake 25 minutes or until a toothpick inserted into the center comes out clean. Let cool in the pan. (Can be made the night before.)
When the cake is cooled, flip onto a cutting board and cut into 1-inch squares.
Beat the cream and powdered sugar until soft peaks form. Put the lemon curd in a mixing bowl and whisk in about 1/3 of the cream. Fold in the rest of the cream.
Combine the berries.
Spread a thin layer of the lemon cream in the bottom of a trifle bowl or glass serving bowl. Spread a layer of cake squares, followed by cream, then berries. Repeat layers until bowl is filled.
Cover and refrigerate until serving. Can be made a day ahead.