Polka dots were the theme for my sweet daughter's first birthday. I made her invitations by printing the details on a simple flat stationery card, then I used a circle cutter to make the balloon shape and attached the striped paper behind it.
I made her a circle-cut banner, hole-punched and tied together with ribbon; it was suspended across the window in the main party area.
Her 4-inch, two-layer smash cake was topped with homemade strawberry frosting (a little runny in consistency, but what can you do when your guests have already arrived!?). Party goers were served cupcakes with buttercream frosting and pastel M&M "polka dots." Foods shaped like circles were also a hit: bowls of cucumber wheels and crinkle-cut carrots with ranch dressing and fruit kebobs of alternating cantaloupe balls and grapes.
When we had Party #2 for local friends (I know, I know...from now on I'll only throw ONE party per year!), I was able to recycle much of the decor, including the circle pendants for the windows and extra balloons.