Story prompts that pop into my head.

Apocalyptic understanding.

After a war, the radiation kills all plants but the ones in a certain area, crops included. Despite the hefty life toll already caused by the war billions die from starvation afterwards. It's quickly found that the only areas food can grow are in those little strange green spots are actually cemeteries. And the spirits don't really like the living suddenly encroaching on their territory, and people and ghost eventually find an equilibrium. A society pops up with both ghost and people living together, along with the usual societal norms and problems like racism, but between ghosts and people.