Several years ago we were given some of these. They were little “promo” loaves.
“Promo” loaves? Who’d promote white bread? They all taste the same. However, I suppose it could have been advertising. This was in the NY-NJ area.
Just checked in with the mom, she says you are right. Courtesy samples were a thing then. She says if you had a new baby, the pharmacist would send over a whole box of congratulatory samples, including the now toxic baby powder in a little tin. Little tin of aspirin, tiny soap, etc. “Probably cost you $100 on ebay today.”
Ok, I looked it up. Advertising tins. Today you can get a sample of original baby powder for around $20 and it includes the dreaded, hazardous substance talc as the active ingredient. With the recommedation to “use freely” right on the can. :D