Named shirring. Nonetheless, the look it makes is similar to smocking, that is an embroidery technique that’s existed a long long time. But maybe don’t google “what exactly is smocking” cuz evidently it also refers to a thing that has nothing at all to do with sewing… In any case, https://rubber-covered-yarn33197.blog4youth.com/32275065/5-easy-facts-about-rubber-covered-yarn-described