sow, n.² — Green’s Dictionary of Slang

sow n.²

[on pattern of UK grunter n. (2); hog n. (1a); sow’s baby n. (2), but no apparent connection]

(US black) any coin, esp. a nickel (5 cents).

1940		D. Burley N.Y. Amsterdam News 19 Oct, 20: A nickel is a ‘sou’.
1944		‘Jiver’s Bible’ in D. Burley Orig. Hbk of Harlem Jive.