Green’s Dictionary of Slang

grover n.

[the head of US President Grover Cleveland (1837–1908), which is printed on the bill]

(US) a $1000 note.

[US]D. Jenkins Life Its Ownself (1985) 163: There was nothing Big Ed couldn’t handle with Grovers. Grover Clevelands. Thousand-dollar bills.
[UK]T. Fontana and B. Winters ‘U.S. Male’ Oz ser. 3 ep. 5 [TV script] Put me down for five Grovers on Khan.