Ha, that's hilarious, Suntiger. Love it!
It's hard to pick just one positive lesson my mother taught. When I was little, she opened the trunk of her 50s clothes like your mother did, April, and let me play with the glamorous things I found there. She sewed most of my clothes (and some of her own), and very early on, she gave me choices -- what colour did I want the dress to be, what style of collar or sleeve (from the options on the pattern), what fabric (within parameters). This helped me develop my own taste. She taught me how to recognize quality construction. Later, as a teen, I had a clothing allowance, which taught me how to prioritize purchases and figure out what I could afford. In my early teens, she took me and my friends to the big city so we could shop there instead of at our boring suburban mall -- this was so freeing and so fun!
She loved clothes herself, but there was a period when, for a variety of reasons, she didn't spend much money on herself and let her style completely flounder. So in the 80s, when I worked in fashion retail during college, I was thrilled to be able to invite her to the store where I worked and encourage her to buy herself a whole new wardrobe following a major life transition.
I guess the best lesson she taught me was to have fun with fashion!