This year's Pi day was low-key. We had miniquiches from Costco for breakfast, I had leftover pizza (pie) for lunch, dinner was normal because we had to get to an event. But the school office was full of pies waiting for kids to pick them up for math class! I guess DS's class didn't observe it this year?
In 3rd grade the kids had a Pi-recitation contest. DS took it out to, I don't know, a couple hundred places, and won by over a hundred. Not an official school event, just the 3rd graders decided it would be fun.