Green’s Dictionary of Slang

1. (US black) explain yourself, what are you up to?

1934		‘Jiggs in “Phew”’ [comic strip] in B. Adelman Tijuana Bibles (1997) 15: What’s the story?
1939		Pittsburgh Courier (PA) 29 Apr. 11/1: What’s your story morning glory?
1944		Cab Calloway New Hepsters Dict. in Calloway (1976) 261: what’s your story? What do you want? What have you got to say for your-self? How are tricks? What excuse can you offer?
1944		C. Himes ‘Let Me at the Enemy’ in Coll. Stories (1990) 37: I jumped up. ‘What’s your story, morning glory?’ [Ibid.] 40: That’s my story, Mister Glory.
1952		C. Brossard Who Walk in Darkness 66: What’s his story? Is he a fruit or something?
1958		Hughes & Bontemps Book of Negro Folklore 488: what’s your story: [...] What do you want? Why? Explain yourself. What’s your story, morning glory?
1969		‘Iceberg Slim’ Pimp 120: What’s your stupid story?
1975		I. Faust Star in the Family 230: If someone asked Mitch, what’s the story, morning glory, he would riposte with, ‘Ask the Shadow, the Shadow knows.’.
1982		G. Newbold Big Huey 154: ‘OK, what’s going on? What’s the story?’ he demanded.
1995		J. Cameron Vinnie Got Blown Away 159: Word gets about. So what’s the story?
2000		N. Barlay Crumple Zone 3: What’s the story? You just had to hang out here specially to see me right?

2. (orig. US black) a general greeting: how are you? [grew in popularity in the UK after the 1995 release of (What’s the Story) Morning Glory? by Oasis].

1942		Pittsburgh Courier (PA) 22 Aug. 7/7: What’s your story, morning glory? — [...] what’s the news?
1946		Mezzrow & Wolfe Really the Blues 47: Man, what’s your story, bring on that sugar.
1948		(con. 1944) N. Mailer Naked and Dead 616: What’s the story, Jack?
1958		Hughes & Bontemps Book of Negro Folklore 488: what’s your story: How are you?
1983		R. Price Breaks 125: ‘What’s the story, morning glory?’ I grinned.
1992		D. Pinckney High Cotton (1993) 59: Uncle Castor climbed from the passenger’s side [...] ‘What’s your story, Morning Glory?’.