Green’s Dictionary of Slang

cab n.2

also cabb
[abbr.]

cabbage.

[UK]Barrère & Leland Dict. of Sl., Jargon and Cant.
[UK]C. Beaton Cecil Beaton’s N.Y. 135: Restaurants, whose plate-glass windows advertize in Bon Ami lettering that ‘snouts plus cabb’ are fifteen cents, and pea soup five.