Srbo. I am not sure about Canada customs regarding Valentine's Day and children. As you know I am well up there in age(72) and celebrating Valentine's Day has been part of my entire life. I do recall giving and receiving drawings, treats, cards even in kindergarten. By third grade it was a big event.
I am a little surprised that your daughter's teacher did not send home a reminder of the days event at her school. Way back when, students would actually have the other students name on the card. In time, it became more politically correct to have 'each' child receive a card, thus no names on cards. The teacher would provide a list of the students within her class and the parents would then know the number of cards to provide.
Again, back in the day, some parents would bake cookies, or cupcakes. Now, all food has to be store bought and individually wrapped. If a family could not afford cards, often the parent would help the child make simple cards from colored paper. And often, again, in my day, the teacher would have extra cards available.
Valentine's Day for child is more about caring and sharing. Not the adult meaning of "Love". I guess in a way, a child's Valenine's Day is a Friendship Day.
Again, it does concern me that the teacher did not mention this event in advance. Does your daughter's school have an event calendar?
Do not worry, Srbo, it is just a fun day for the children , and as you said, your daughter came home all happy and had a good time. That's what it's all about for a child. Not the "adult theme", but rather a day at school to have fun. Hope that helps.