Who said decorating is for Christmas alone? A couple weeks ago, I stopped at Target and picked up a three dollar "Special Delivery" Valentine Mailbox. A family can put handwritten notes in the box until Valentine's Day, and then open them all up.
The heart and the garland were a buck-a-piece at Dollar Tree, and the chain links and drawings were free with use of our own construction paper.
Next year, the plan is to make more runs to the dollar store for more decorations over time.