I always loved May Day when I was little! We would make bouquets and put them by our neighbors' doors, ring the doorbells, and try to run away before they saw who it was...though we probably weren't successful :).
I rounded up a few ways to celebrate this year, starting with the classic paper cone bouquets we used to do:
These "seed bombs" would be so fun to make for a preschool class!
I've been looking for flower crown tutorials everywhere, and this is the first one that made me think "I'd actually make that!" So cute, and I can get all of the materials at one place (maybe I'm not a real mom yet, because I don't own a hot glue gun. I just have to ignore any DIY that requires them, so floral tape seemed genius here!).
And for the really ambitious, the kids would think you were a hero (or maybe a fairy) if you made a Maypole for the yard!