Pulse the sandwich cookies in a food processor until fine crumbs form. Set aside 1 cup of crumbs for the top "dirt" layer.
In a large bowl, beat the cream cheese and powdered sugar until smooth.
In a separate bowl, whisk the milk and pudding mix for 2 minutes until thick. Fold into the cream cheese mixture, then fold in the whipped topping.
Layer half of the remaining crumbs in a trifle dish, then half of the pudding mixture. Repeat both layers.
Top with the reserved 1 cup of crumbs. Push the wafer-cookie tombstones into the "dirt" and scatter the gummy worms and candy pumpkins on top.
Chill at least 2 hours (overnight is even better) before serving.