Are you thinking for Mother's day, or for May in general.
1. Pick a mother figure, sibling who takes that place, person you see as important male or female and bake them cookies, make a card, or just say thank you for what you do for me.
2. May 1st, pick May flowers and make little boquets. (Be sure to ask permission to pick flowers) and then leave them with people who are meaningful to you. They can be teachers, case workers, or the person at McDonalds that always gives you extra fries! Tell them, Happy May Day!
3. Cinco de mayo is May 5th. Here is info on ways to celebrate: https://en.wikipedia.org/wiki/Cinco_de_Mayo