Use the spool of thread to create your circle then cut on the line. Next, thread a needle using a long piece of thread ( I used buttonhole thread in a contrasting color for the visual if using regular thread use a double strand) and stitch around the circumference far enough from the raw edge that the fabric will not fray.
Gently pull the thread to gather the circle in. The edges should naturally tuck in but you may need to coax them a bit. You will end up with a flattened circle:
On the flattened button, repeat the above step, stitching around the folded edge. ( I forgot to take a picture of this step) Firmly pull and shape til you get the button.
Take your needle and stitch across the opening using the gathering as a guide.. and Viola you have a button.. Leave a long tail so that attaching to the garment will be easier.
Making fabric buttons was easy and they match the dress. Give them a try and see what you think. The cost of pewter buttons for a cotehardie can be very high as you need sooooooooo many. This is a great alternative and is also period. Have fun!!