My first guess is ruffler or pleater. My mom had a very old machine that came with a lot of attachments, one was a ruffler. The machine was controlled by a knee control, my dad converted it to be used as a foot control, great old machine. I used the ruffler and Rosemarie is right, works very well. Wish I had all those old attachemnts and they would actually fit on my modern machine. They were great.