Green’s Dictionary of Slang

a coin of small value, usu. a penny.

1895		Mirror of Life 9 Feb. 6/4: We never attempted to ‘touch’ Jack for a ‘coalheaver,’ and we think it is only beauty in distress that would make Jack play the game of ‘shell out’.
1925		(con. WWI) Fraser & Gibbons Soldier and Sailor Words in DSUE (1984).
1935		Thieves Slang ms list from District Police Training Centre, Ryton-on-Dunsmore, Warwicks n.p.: Coal heaver: Penny.
1960		J. Franklyn Dict. of Rhy. Sl. 51/1: Coal heaver Stiver (a penny), late 19C. Reduced to coal, and misspelt cole.