This is the package it's from Clover called Bag's & Tote's, ,magnet tote bag closure 3/4"Get you local fabric/quilt store to get them for you, they are really fast.
I included the directions, from the back, (sorry about the bad photo) but you make two little slits in your fabric, put the prongs through, add the top on the prongs, bend the prongs .....THAT IS IT! It was about $4.00, but well worth it.
P.S. Here is a photo of the yo-yo buttons I put on my bag. I made a yo-yo and used a 1 1/4" covered button!