First fold sheet of 8-1/2 x 11 paper in half to form card (to a size of 4-1/4 x 5-1/2).
Cut front panel of cereal box apart from rest of box. Trace heart shapes* onto the piece you just cut out. Cut heart shapes out of cereal box board to make stencils for cutting lots more hearts. *(Either draw freehand several sizes of hearts and cut out, or print out the patterns below and glue to board from cereal box and then cut out.)
Use your new cardboard stencil hearts to trace as many hearts as desired on the back side of selected wallpaper samples, colored paper, or whatever and cut out.
Glue hearts on card to form desired patterns and let dry.
You can also continue decorating on the inside of the card if you like.
Don't forget to add your Valentine greeting and message to your special card.