In 3-quart saucepan, melt butter over low heat. Add vanilla and marshmallows; cook, stirring constantly, until marshmallows are completely melted. Remove from heat.
In large bowl, place crumbled baked cookies and popcorn. Add marshmallow mixture; mix lightly until everything is evenly coated. Cool 1 or 2 minutes.
Line cookie sheet with waxed paper. Spray hands with cooking spray to prevent sticking. Shape mixture into 20 to 25 (2- to 3-inch) balls; place on cookie sheet. Sprinkle balls lightly with decorative sugar.
Insert lollipop stick halfway through each ball, squeezing ball with hands so it forms to stick; return to cookie sheet. Let stand until mixture is firm, about 20 minutes.
When balls are firm, cover with plastic wrap and tie with ribbon to give as a gift.