white electrical tape (could use masking tape also)
green construction paper
First cut a hole in the top of the box for the Valentines to be dropped in. Then cover the entire box with green construction paper. Don't worry about making it perfect, when you are done covering the box in green paper you will take the electrical tape and cover the edges of all the paper. This gives the box a more clean look and adds to feel of a real football field. Use the popsicle sticks to creat goal posts. You can glue them together if you want. For speed and ease, we just wrapped electrical tape around the corners of our popsicle sticks and then used the electrical tape to tape them to the ends of the box. Finally, I gave my son a sharpie and he went to town creating the field. He loved drawing all the lines and trying to make it look exactly like his favorite team's stadium. He even drew stick figure players and his own scoreboard.
Happy Valentine's Day!