First day was using detached buttonhole stitch to attach small objects to fabric. I've never been totally sure of the difference between buttonhole stitch and blanket stitch, but it seems that standard buttonhole is just blanket stitch with the stitches close together (although there are variations on buttonhole which are more complex). Buttonhole certainly sounds more complex and professional, not least as blanket stitch is often one of the first stitches taught to children - I distinctly remember the blue felt recorder case I blanket-stitched in junior school.
For our purposes, the coins were covered in silk organza stab stitched to hold the coin in place whilst the buttonhole was stitched (the idea is that the stitching eventually holds the coin firmly enough that the organza can be shredded and pulled away). The first row of buttonhole was stitched very closely to the edge of the coin, and then subsequent rows were stitched into the previous row (this is the 'detached' element, the stitching is detached from the fabric, as distinct from e.g. detached chain stitch where the stitch is detached from the other stitches).