Green’s Dictionary of Slang

(US Und.) a fake wad of money used in a confidence trick.

1997

L. Pettiway Workin’ It 109: He had a knot full of money, but it’ll be money on top ... It’s a mitch, they call it, but it don’t be nothing but a green dollar bill or something on top of this mitch. You just got to convince somebody to put their money with your money. Supposed to be your money, but it ain’t no real money there.