Somebady said that this is the Barbie-doll's bag!

Make a piece of crochet (here knit-stitches). It must be about 3 times the coin you usually need.
Make a basic row on the two long sides - in another colour, if you like. 

Make a handle with a basic row.

Sew the little purse and and a button as in photo.

Your purse is ready to join your bunch of keys!

   
To the little light red purse I made a crochet chain.