So, in the original Golden Age Green Lantern stories, Solomon Grundy started unlife as the corpse of a dead nineteenth century prospector, Cyrus Gold, who perished in Gotham's Slaughter Swamp. According to the mythos, Gold's corpse steadily accumulated plant matter until he reanimated as a chalky skinned behemoth whose plant matter substance rendered him invulnerable to Alan Scott's power ring given its susceptibility to wood. Because of that, he became a formidable foe for Alan and later, for the Justice Society of America. The problem is, this doesn't go into sufficient detail. Given Earth-Two's greater magical propensities, it could be argued that Slaughter Swamp may be an abandoned Native American shamanic reservoir or burial ground, and that might be what animated Grundy. It might be the case that an elderly witch or magus lived in the vicinity too and that there's residual magic from that period still in the environs of Slaughter Swamp. Although, there are also rationalist explanations possible.

In my Justice Alliance Earth-500 Infinite Earths series, I've just introduced Shulamith Grundy, a female version of tall, chalky and gruesome. In her case, she was a mob hitwoman, ambushed and dumped in Slaughter Swamp and there was an under-regulated chemical factory which was  pouring its effluent output  into the swamp. It reacted with Shulamith's corpse, and thus...of course, there are other possible scenarios. Say Solomon could be the product of a nuclear waste dump leak and biomutations, or from the interaction of his body with a hitherto undetected zoopathogen micro-organism, or parasitic organisms of some sort, or... or, whatever rationalist scenario you might want to suggest. 

So, how about it? Is it time to tweak and embellish Solomon Grundy's origin and add some background detail? Or should we leave well enough alone?

Source: "Fighters Never Quit" All-American Comics 61 (October 1944): dc.fandom.com/wiki/All-American_Comics_Vol_1_61

This Wikipedia article contains some useful detail about reiterations of the character: en.wikipedia.org/wiki/Solomon_Grundy_(character)