rolling billow, n. — Green’s Dictionary of Slang

rolling billow n.

[rhy. sl.; later joc. use in Borough market, S.E. London, for sacks of potatoes]

a pillow.

1957		G. Kersh Fowlers End (2001) 131: To Bo-peep on their rolling billows [...] Where their loaves o’ bread repose.
1972		Dodson & Saczek Dict. of Cockney Rhy. Sl.
1984		Partridge DSUE (8th edn) 985/1: late C.19–[...] 1960.