I like the idea of using a polka dot backdrop like this for pictures.
Dramatic Play: kids can shop for party supplies FREE printable Polka Dot Party Hats (+DIY pompom tutorial)
confetti filled balloons, sprinkle party Fill clear balloons with large confetti~Black & orange for Halloween, school colors, etc.
Possible Tableware for Painting Party Theme Polka Dot Party Standard Kit
Polka Dot Party - I like the gumballs in containers and the hats with pom-poms
Sweet Shoppe Lollipop Party Printable Labels for by tomkatstudio
Polka-Dot Party Favor Bags to keep the kids busy (when they get too tired for anymore carnival rides).
pretzels white candy with purple sprinkles