i remember having safety pins around all the time when i was little. mom had them on her apron, in any given drawer, in a special little glass dish on her dresser. more often than not, they were for the potential broken bra strap, but they came in handy. and i remember them being sold on cards, and the little ones were called "beauty pins", because they would keep the top of your slip from showing over your dress, they would mend that strap, or temporarily fix that garter that wanted to give out. and they sold them colored--most often brass or gold, but the black ones were to use on your navy blue or black dresses/slips/underwear. they were as common as hairpins were, back then.
my youngest daughter fell in love with the bigger ones as a fashion statement when she was a teen--big safety pins, and duct tape on everything!