Even though these are 'consumable' items, probably a great many of these cards survive - like these.
An amazing amount of these snap-fasteneres were jammed in in an old jam-jar. Amongst a load of fairly recent generics (for offspring to craft with), a surprising number of older cards. Many with the original product still on the card. A snapshot of haberdashery packaging from probably the late 1930-ies to the late 1960-ies.
Some cards have used fasteners snapped back onto a card - waste-not, want-not!
Some of the older Koh-I-Noor buttons/fasteners have an unusual 'castellated' rim, neat. The spelling of the advertising on the back of these does suggest a date no later than ~1950. (Dutch spelling evolves rather.) The one card that was the lower-corner of a sheet carries what is probably a printer's mark 'I 40', quite likely 1940.
Another little bit of trivia this threw up; there are a few 'Prym' cards in there as well. This company is still in business and has been producing metalwork since 1530. Still makes snap fasteners too.
Not quite so ephemeral :)