A pocket with an expansion pleat around the edge to provide volume and a 3D look!
Mark the fold lines & corner points with chalk, interface the top of the pocket, press & fold over.
To form the bellows pleat, with right sides together fold the bottom corners in half matching the points & angles, stitch along the line, pivoting the needle at the 90 degree point & ending the stitching at the 1cm seam allowance point.
Snip into the corner point & cut off the seam allowance as shown below.
Press open the seam allowance & turn the corner through, tease it out to look sharp & press.
To finish pocket top press under the seam allowance & top stitch.
Press pocket lines, fold back & press bellows lines, these should form naturally from the bottom corner points already sewn.
Press remaining seam allowance under, pin in position onto the garment & top stitch in place.
Below shows a variation where the pocket edge has been topstitched & a flap added.
Garment Construction 