Celery flower art is another great Mother's Day idea or just a simple art project for the classroom. I think the idea of using food to create art would be an interesting project to bring to the classroom and have students work with and experiment with.
I love you clothes pins: Write a message with a FINE POINT sharpie so it doesn't smear. Write "I love you" on a paper. Cut it out, and hot glue it to the clothes pin end. Would be cute for a care package!