Green’s Dictionary of Slang

1. (US Und.) morphine.

1935

A.J. Pollock Und. Speaks.

2. (Aus. prison) marijuana.

1971		McCalls Mar. 97/2: ‘Picked up two freaks loaded with margie-wanna,’ one Task Force man will say, to open the ego contest.
1990		Tupper & Wortley Aus. Prison Sl. Gloss. 🌐 Margie. Marijuana. Corrupted diminutive.