Fist thing you do is get some white felt and cut out two rectangles with rounded corners, using a playing card as a template. Then make one smaller rectangle which fits inside the bigger rectangle for the back. The traditional colours to use for this is red, black or blue, but anything goes really. Cut this with pinking shears for a nice edge.
Make cross stitches all along the smaller rectangle in rows. Doesn't matter whether they're even, just have fun. You can try out different designs if you fancy yourself an embroiderer! Stitch your rectangle on to one of the white ones.
Cut out one bigger and two smaller card suits for the front (suits: red hearts, red diamonds, black spades, black clubs. Experiment with colours and designs if you want!) and stitch them on to your other rectangle, the bigger one in the centre and two smaller at opposite corners. Then sew your two rectangles together. Take a small, long rectangle and attach around the centre to make it a bow.
Attach a hair clip or a pin at the back. You can use these as hair accessories, brooches, sew them on to clothes, or make a pair and use them as shoe clips! I'm sure you can think of more uses too :)