Elizabeth Hawes - Fashion Is Spinach (1938)
Yes, I mainly chose this for the title but it turns out to be an attack, good-natured but an attack nonetheless, on the fashion business done by an insider. The praise of French designers, how fashion has no use for the average person, the inexplicable changes, the behind-the-scenes troubles. If nothing else you'll learn more about artificial silk than you probably ever wanted to know. This may sound a bit sarcastic but I suspect that this book's criticisms are as true now as they were when it was written. (In 1954 the author published It's Still Spinach.)
Elizabeth Hawes (1903-1971) was born in New Jersey, studied in Paris and ended up a famous designer. She strongly supported the idea that people should have clothes that they were comfortable with and that worked for them, not something chosen by the fashion industry.