Our school has a "nutrition policy" that we can't send in any homemade treats and no treats with sugar in the first 3 ingredients. Well that really limits things for Halloween and Valentine's day and makes it that parents can get creative.
One year Robert made "gum people" http://schickfunideas.blogspot.com/2011/02/roberts-school-valentines.html this was an idea from Family Fun Magazine
Another year we made Shrinky Dinks http://schickfunideas.blogspot.com/search?q=shrinky+dinks as zipper pulls or pins.
But a couple of other ideas for school acceptable treats
Juice pouches or boxes with it labeled as "You're squirting fun"
At this point in the year the kids can us a sharpened pencil - "You are a Sharp one" written on a paper heart with 2 little slits that the pencil can be poked through
Or a cute Valentine's eraser - take double sided tape and tape it to a heart cut out and then write - "There's no mistake Valentine"
These are just a few ideas that might make preparing for a school Valentine's Day party a bit easier!