Crush Oreos. Put 1/3 of the crushed Oreos into a new, clean flower pot. Set aside.
Mix butter, cream cheese and sugar and vanilla together. Set aside.
Combine milk and pudding mix. Fold Cool Whip into the pudding.
Fold together pudding mixture and butter-cream cheese mixture.
Layer this mixture (about 1/3 of it) onto the crumbled cookies in the pot. Next, add another layer of the pudding mixture, then another layer of cookie crumbs, continuing until all ingredients are used.
As you're layering the ingredients, decoratively place several gummy worms and critters in the "soil" so they will be seen emerging. If you have a toy (clean) garden trowel, a plastic daisy, or some edible flowers, these can also be used creatively to embellish the presentation.
Chill in refrigerator for 3 to 4 hours before serving.