Inseam pockets are easy to add to a garment.  Each pocket consists of 2 identical pieces that are shaped like a  thick drop coming out of the end of a straw.  The "straw" has about a 7" opening.  This straight edge is sewn to the seam allowance with a 1/4" seam on both pieces of the garment where you want the pocket.  (Be sure that the pocket will not extend beyond the garment edges when sewn in.)  The pocket pieces are now one with the garment pieces and the original seam line is interrupted to turn and sew the pocket seam before turning again to finish the garment seam.