When it comes to sewing things onto her crocheted pieced, The Animator's Wife, being the frugal lady that she is, does not like to have to buy sewing thread to match whatever yarn she's been using. That just seems wasteful, buying a whole spool of thread for just one little embellishment. On the other end of the spectrum, sewing with the same yarn you've been using for the rest of the project can be problematic when sewing embellishments with predrilled holes, as often times the yarn is too thick to fit through the holes.
This is what The Animator's Wife does in such situations. This trick will work with any plied yarn, meaning yarn that is made from multiple strands of fiber that are twisted together. If you're using thick, single-ply yarn, you'll have to resort to using sewing thread.
Thread one or two of the strands into your sewing needle and use them just as you would regular sewing thread.
Now you have a tidy little button that perfectly matches the rest of your project.