Original vintage quilted maxi, buttoned side slit

Groovy maxi skirt, teen 1960s? The best part is this long button placket on side slit, hard to photograph. Waist is 24”, smaller than my dress form. You can see the machine quilting, Black stitching on floral fabric, inside is unfinished quilting material, no lining. Some gathers at waist band, pretty straight down from there.