"Sheerio" trademark registered in 1934, but was in use as early as 1931. The trademark was renewed by Van Raalte in 1974. It is now dead.
Here is a great Sheerio Ad from 1949
A superb PHYLMY full slip with embroidered chiffon Empress Jade Vintage
A delicious crystal pleat Sheerio nightgown and a rare Sheerio teddy both courtesy of Heavenly Vintage Lingerie
A pale blue flounced Sheerio nightgown with embroidered chiffon - courtesy of Heartsvintage