Ask for donations of Kleenex boxes early to make sure you have a good amount for the number of children you expect at your St. Valentine's Day event. You can cover the boxes with construction paper beforehand, or allow the children to cover them on their own. Use die cuts to create shapes such as hearts, castles, fairies, dragons, and other Valentine-related shapes. These can be used to decorate the box. The children can then use the box as a mailbox for all of their Valentine cards.
I have not yet managed to collect the 30 boxes I was hoping to have by Valentine's Day, so I came up with a quick and easy craft that children could do if there were not enough boxes. As it turns out, I love this craft just as much, and I'm not sure which of the two is my favorite. This craft consists of cutting the top of a brown paper bag about an inch or so, and decorating it with a Cat, Dog, or Giraffe template and heart. I found this adorable idea over at Craft of the Day, a daily craft blog from the makers of The Best Kids Book Site. There is also a very cute Panda Bear template you can use as well.
You can also check out this adorable Dog Box for Valentine Cards from DLTK.
And finally, this last craft was originally from Family Fun (by Disney, which is now Spoonful, I believe). You take the Conversation Hearts by Brachs or Sweethearts (there are also some small Valentine tattoos at the stores that would work), and you cover them with construction paper and an iPod template to create the illusion that it is an iPod. You can pretty much use any candy, however. There was a box of 30 Twizzlers and Jolly Ranchers (15 of each) that was much cheaper than buying conversation hearts, and that is what I decided to use. The candies were covered with construction paper and tape, and the iPod template was glued on the front. The adorable iPod template was incredibly hard to find, especially with the moving around on the Family Fun crafts site to the Spoonful site, but I was able to find it. I can't find the exact link I used, but I did find it available for download on this site. The iPod (or iLove) shows Valentine songs, but you can edit the template to add your own songs. For this craft, I added the following book titles: Bunnicula, Diary of a Wimpy Kid, Goosebumps, and Harry Potter.
You can see Reese's candy because you can add two strings to the iLove and attach one Reese's peanut butter cup (small) to each string to create headphones! Very cute indeed.
You can visit these websites to see how others have created Valentine iPods.