Are you thinking of the HERCO plastic finger picks? I used 'em for years. Came in little plastic boxes that fit into a larger shop display. These picks would stay good for a long while---unless you rolled over on em while they were in your pocket---or just got weakened by contant on-putting and off-pulling until they were brittle. When I couldn't find 'em in stores any more, I went to the Dunlop metal picks and used those the rest of my picking years. But nothing gave you a mellow sound like the HERCO plastic finger picks. Metal picks always had a strange clangy metallic attack sound when the pick contacted a metal string that I never really got past.

Art Thieme