I have spent the week pondering the single strand stopper knot.
My preferred choice is the button style also known as the celtic button, chinese button or turks head stopper. My usual references were a bit confusing so I thought I would post a video for next time I need to tie the knot. The instructional part of the video is in the first 20 seconds. The remaining 40 seconds is just working up the knot so that it is neat and tight.