Ric rac

Rickrack (sometimes spelled ricrac) is a "flat narrow braid woven in zigzag form, used as a trimming for clothing or curtains." Before the prevalence of sewing machines and sergers, rickrack was used to provide a finished edge to fabric.

Made of cotton or polyester, rickrack is stitched or glued to the edges of an item. Its zig-zag configuration repeats every third of an inch (about one centimeter) and is sold in multiple colors and textures. Rickrack's popularity peaked in the 1970s and is associated with the Little House on the Prairie and the pioneer sentiment brought about by the 1976 American bicentennial.

Several designs of formal and up-market girls' dresses with it on as a decoration became popular in the 1950s and 1960s. They are now considered a vintage classic by some, but tacky by others.

...
Wikipedia