1. Place popcorn in a large bowl. Melt 3 Tbsp. butter in a medium saucepan over medium heat. Stir in vanilla, marshmallows and salt. Continue to stir until smooth.
2. Pour marshmallow mixture over popcorn and mix with a wooden spoon to coat. Grease your hands with a thin layer of softened butter, then shape popcorn mixture into 10 balls and place on a piece of parchment or waxed paper. Press M&Ms into balls so they adhere. Insert 1 ice-pop stick into each ball. Serve. (Position in pails to look like flower arrangements.)