Green’s Dictionary of Slang

(drugs) a marijuana smoker; also attrib.

1939		Champion Jack Dupree [song title] Weedhead Woman.
1947		R.O. Boyer Dark Ship 152: He was a weedhead, and trigger-happy.
1956		N. Algren Walk on the Wild Side 161: The right arm bore a strange tattoo: A narrow cigarette whose smoke formed a burning boast: king weedhead.
1965		C. Himes Cotton Comes to Harlem (1967) 180: Now I know why the world looks so vague to weedheads.
1978		(con. 1964) J. Carroll The Basketball Diaries 27: My cousin Kevin did introduce me to a few weed-heads up here once, and today I ran into them and goofed with some ball playing.
1980		S. McConville ‘Prison Language’ in Michaels & Ricks (1980) 525: A smoker of cannabis may be called a pothead or a weedhead.
1994		Rebennack & Rummel Under A Hoodoo Moon 128: I’d show up with a joint in my mouth, signifying I wasn’t no dope fiend, just a weed head.
2007		B. Coleman Check the Technique 173: ‘The theme of that song [“Nickel Bags”] was us being college weedheads, but we wanted to talk about it using music as a metaphor instead’.
2021		J. Ellroy Widespread Panic 214: [W]inos, weedheads, K-Y cowboys.