Green’s Dictionary of Slang

1. (US) a top hat.

1865		in B.L. Ridley Battles and Sketches of the Army of Tennessee (1906) 460: See a fellow with a Bee Gum hat ride down the line, ‘He’s a gentleman from the States’.
1873		Bloomfield Times (PA) 18 Mar. 2/4: He had [...] a high bee-gum hat.
1880		J.C. Harris Uncle Remus Songs 230: One er deze yer slick-lookin’ niggers, wid a bee-gum hat an’ a brass watch ez big ez de head uv a beer bar’l, come ’long an’ bresh up agin me.
1895		Lafayette Advertiser (LA) 26 Oct. 6/3: [They] sent out a committee to git me some new riggins. They lit out they did and got me a three-story beegum hat, a ruffle-bosom shirt [etc.].
1903		Central Record (Lancaster, KY) 6 Mar. 1/5: ‘Tubby’ Wilkerson appeared [...] in a cracker-tail coat, doe skin breeches and a bee-gum hat.
1904		DN II 416: Bee-gum hat ... Silk hat. ‘You must wear a bee-gum hat at the laying of the corner-stone’ (addressed to the worshipful master of a Masonic blue lodge).
1904		J.W. Carr ‘Words from Northwest Arkansas’ in DN II:vi 416: bee-gum hat, n. Silk hat.
1918		Chariton Courier (Keytesville, MO) 1 Mar. 7/1: He neither wore a bee-gum hat, nor a dress suit of the cutaway pattern.
1929		J.F. Dobie A Vaquero of the Brush Country 185: Over in England [...] Tom would retire to his dressing room after the performance was over, take off his cowboy clothes, emerge in attire of the latest fashion, including a beegum hat, and then mingle with admiring nobility.
1939		FWP Guide NC 505: In this section any high hat is called a ‘beaver,’ or, in derision, a ‘bee gum.’ [DARE].

2. a hairstyle in which a woman piles her hair on the top of her head.

1967

in DARE.