Green’s Dictionary of Slang

a potato, usu. pl.; thus (US short order) murphy with his coat on, an unpeeled boiled potato.

1810		‘Paddys Wedding’ in A Garland of New Songs (5) 3: Now a roaring set, / To dinner are met [...] With murphies galore.
1812		Spirit of Irish Wit 171: And though the Murphies are but small / O make them large enough for all.
1821		‘An Amateur’ Real Life in London II 165: The murphies are cracking, the salt-herrings scalding, and the apple-dumplings tumbling about the pot.
1827		Egan Anecdotes of the Turf, the Chase etc. 151: Mathews relished the Irish stews and murpheys.
1831		Satirist (London) 26 June 93/1: Alack the day! Lord Tamworth of that ilk, / When you, for Maynooth murphs, forsook your mother’s milk!
1832		Egan Bk of Sports 38: Let me have them [i.e. mutton chops] nice and hot, / With a murphy and chalot.
1840		‘The Royal Nuptials’ in C. Hindley James Catnach (1878) 315: A shipful of harrins, tin cart loads of murphies, Garman sausages with ind.
1847		Bell’s Life in Sydney 13 Mar. 3/1: Pretty much in the style of a patato [sic] porter dragging a bag of the ‘murphies’ after him.
1851		‘Dear Praties We Can’t Live Without Them’ in Irish Songster 37: Eat plenty of murphies, and d--n the expense.
1858		A. Mayhew Paved with Gold 66: I think I knows where there’s a potato-field, and if one thing is primer than another it’s baked ‘murphies’.
1860		N.E. Police Gaz. (Boston, MA) 18 Aug. 8/3: Seth [...] refuses to receive a single cent in payment for beef-steak. However he demands twelve cents for the same, as usual, with murphies.
1861		(con. 1840s–50s) H. Mayhew London Labour and London Poor I 175/1: He can always have a hot murphy.
1877		Northampton Mercury 28 July 7/5: The potato-bug is [...] the most formidable adversary [...] those early ‘murphies’ disappeared.
1884		Aberdeen Eve. Exp. 2 Oct. 2/3: The ‘hot potato — all hot’ business [...] is not sufficient to supply the craving of the purchasers of roasted ‘murphies’.
1887		‘Dict. of Diningroom Sl.’ in Brooklyn Daily Eagle 3 July 13: ‘Murphy with his coat on,’ is a boiled potato, unpeeled.
1888		Telegraph (Brisbane) 28 Sept. 5/1: Irish bog oranges, commonly called murphies.
1899–1901		(?) H. Lawson ‘Getting Back on Dave Regan’ in Roderick (1972) 366: He left [...] a bag of potatoes for Murphy the storekeeper at Home Rule an’ a note that said: ‘Render unto Murphy the things which is murphies’.
1902		Bulletin (Sydney) 27 Sept. 17/1: In days that are gone we spent part of each year / Digging spuds till the season was done, / And few were the grafters and ‘murphies’ were dear, / And grand was the wage to be won.
1903		Ocala Eve. Star (FL) 7 May 3/4: Pittman’s Praties. Mr J.A. Pittman has an Irish potato patch which has supplied him and his family with all the bog oranges they could eat. Mr Pittman was showing one of the murphies yesterday.
1910		Ocala Eve. Star (FL) 20 June 1/5: ‘Where’s my baked potatoes?’ asks a customer. ‘Mrs Murphy in a sealskin coat!’ shouts the waiter.
1914		E. Pugh Cockney At Home 174: Jest a pound o’ meat, and a pot o’ beer, wi’ some murphies and a bit o’ cabbage.
1921		N&Q 12 Ser. IX 347: Murphy. Potato.
1930		(con. 1900s–10s) Dos Passos 42nd Parallel in USA (1966) 127: Janie nursed some murphies baking in the ashes.
1936		Mencken Amer. Lang. (4th edn) 566: There are, indeed, slang terms that have survived for centuries, never dropping quite out of use and yet never attaining to good usage. [...] Among nouns, gas for empty talk has been traced to 1847 [...] murphy for potato to 1811.
1949		Monteleone Criminal Sl. (rev. edn).
1959		I. & P. Opie Lore and Lang. of Schoolchildren (1977) 183: Potatoes are ‘murphies’.
1989		H. Rawson Dict. of Invective (1991) 210: For reasons that should not seem terribly obscure, the Irish potato also have been known as a bog orange, Donovan, Mick, or murphy.
1995		E. Kelly Apprentice 40: When you sat down to such a meal there was a mountain of laughing Murphies in the middle of the table, and as that mountain went down a small mountain of potato skins rose at each elbow.