Place popcorn in large bowl.
Place marshmallows and butter in medium saucepan over medium-low heat. Stir until marshmallows are melted and mixture is smooth. Remove from heat.
Stir in vanilla extract.
Pour mixture over popcorn in bowl. Toss well to coat popcorn evenly.
Line baking sheet with foil.
Spray hands with nonstick cooking spray then scoop up about 1 cup popcorn mixture.
Shape mixture into cone, keeping base flat to form tree.
Sprinkle tree with decorating sugars; place tree on baking sheet.
Make nine additional trees.
Pipe frosting on trees to make garland then decorate with sprinkles and silver dragees, as desired.