Green’s Dictionary of Slang

1. (orig. US) insignificant, irrelevant.

1836		Bangor Whig & Courier (ME) 29 Dec. 2/2: So much for political humbig and small potato politicians.
1846		N.Y. Herald 13 Dec. n.p.: Give me an honest old soldier for the Presidency [...] and I will leave your small potato politicians and petty-fogging lawyers to those who are willing to submit the destiny of this great nation to such hands.
1849		G.G. Foster N.Y. in Slices 102: Like monkeys and small-potato politicians, they have their appointed end.
1861		N.Y. Herald 2 July 4/5: Old Abe need not trouble himself about the injuries which such small potato affairs may endeavour to inflict upon him [DA].
1882		Nat. Police Gaz. (NY) 3 June 2/2: The small potato legislators of Texas have put a tax of $5.00 on the venders of the Police Gazette.
1895		Truth (Sydney) 28 Apr. 3/3: Reid was glad the Judge had got beans for the way he used to scarify him when he (Reid) was a very small pertater barrister.
1897		C.H. Haswell Reminiscences of City of N.Y. 331: He [...] was in the habit of referring to Governor Seward as his ‘small potato highness’.
1928		M.C. Sharpe Chicago May (1929) 287: He said it was too small-potatoes to bother with, and offered to buy me one.
1981		J. Elllroy Brown’s Requiem 71: ‘I can tell you this: it [i.e. a gambling operation] was just a small potatoes setup’.

2. selfish, mean.

1910

B.L. Bowen ‘Word-List From Western New York’ in DN III:vi 448: small potatoes, adj. phr. Selfish; low-minded; contemptible. ‘That’s pretty small potatoes, to do that sort of thing.’.