Chain 10 (more, or less, for a larger or smaller purse)

Base row (row 1):
sc in 2nd chain and in each chain across
3 sc's in end chain
sc in each chain on the "back" side of the original chain (the loops you didn't use already)
3 sc in end chain

Rows 2 through 7 (or so)
sc in each stitch below. An envelope-type pouch will quickly form. Sc in each stitch below for, oh, six or seven rows. (I work in a spiral, you can work in spiral or round)

When it's "deep enough", stop at one of the pointy edges.  Without disconnecting the yarn, make a strap for a necklace with chain stitches -- about 24" or so (depending upon your DD's head size). Connect this strap to the other pointed edge of the pouch.

You now have an open pouch with a neck string. That won't do -- you need to close it! So, go back and forth between the strings on ONE SIDE ONLY of the pouch -- this forms the flap.

Pick a button. Chain "enough" to be a button loop in the center of the last row of the flap ("enough" being big enough to fit whatever button you have chosen).

Sew the button on. Give to DD. Be ready to make lots more, as her friends see hers and want one!  (Fortunately, they're quick to make.)