I spent most of the day designing simple valentine cards for an article. As soon as I'm done with it I'll post it here. Some are suitable to do with your young children. I tried to pick supplies most crafters already have on hand. Granted we all have different stashes of materials, but most of us have paper, glue, scissors, ribbon, and buttons.
I'd like to also design some cards that use stitchery, but I'm not sure when I'll get to it and Valentine's Day is just around the corner.