Stuffing material (as for furniture and mattresses) made of slender, curled wood shavings, as a substitute for hair.
1942, Elliot Paul, The Last Time I Saw Paris, Sickle Moon 2001, p. 91:
These little mangers, with baby dolls representing Jesus, porcelean Josephs and Marys, wide-eyed cows of papier-mâché, and excelsior for straw, were purchased by pious parents for well-behaved children at Christmas-tide.