It is very easy to make your own football onesie. All you need is a brown onesie (Hobby Lobby was the only place where I could find one), some white or ivory felt, and a needle and thread (or sewing machine). I also used an embroidery hoop to make it easier, but it was not necessary.
Cut one long thin rectangle of felt. Sew it to the onesie using a back stitch. Cut 5 smaller felt rectangles and sew them on. I intentionally make the strips slightly different sizes and sewed them at slightly different angles.
Halloween costume idea: Benjamin as a football player and Lyla as a football.