It is possible to knit your garment and add pockets later. Just knit a sample square in the same colour or even a different colour, even try using lace. Start with waste yarn and end on waste yarn. To sew it on use a back stitch and sew through the whole of the open stitch. It can be attached to a length of ladders from leaving a stitch out of work or a lace pattern or from a seam sewn in at the open end.
Another option is to put the needles into hold and just work on the pocket. Knit double the depth of the pocket and then return the needles to working postion and complete your item. Sew up the edges of the pocket, and all done.
3rd: Valerie - coloured knitted ball with a bell inside
A bit of crafting by one of the members