Popcorn: caramel popcorn or plain is a great choice for a treat board
Make a sweet pumpkin flavored dip and serve it in a hallowed out mini pumpkin
Fruit or Fruit Roll Ups: these can easily fill in small empty spaces on a board. Tip: Dip strawberries into melted white chocolate and pipe eyes on them with black food coloring to create Ghost Strawberries
Decor: plastic spiders, eyeball sprinkles, mini pumpkins, etc.