Not all women in the 1900s wore heavily boned corsets. Some preferred to wear a lightly boned ribbon corset, usually called sports or athletic corset.
Ribbon Corset from 1900 to 1910 (Suede Imitation) – Larva – Historical Dressmaking
Made-to-measure Underbust Ribbon Corset. Great for Edwardian or Everyday Wear. Available With Busk or Zipper Front.
Research: Edwardian Ribbon Corsets Part I – Wearing History® Blog
REF W PDF Digital File Antique Edwardian Corset Pattern 19.40 Inches Waist Size Antique and Pictures
Research: Edwardian Ribbon Corsets Part III – Wearing History® Blog
Edwardian Shirtwaist Costume - Sew Historically
7 1900s ribbon corset ideas corset, corsetry, historical fashion
S-Bend Edwardian Corsets – Lucy's Corsetry
Hand-Embroidered Edwardian Eyelet Lace Camisole - Sew Historically
Ribbon corsets - Recollections Blog
Edwardian Health Corset - Good Sense Corset Waist - Sew Historically