i'm not sure if it's a walnut tree or not, but in the forest preserves
there are these fruits that fall off trees that look and kinda smell
like lime.

if you crack it open, it's all dark and musty inside. if you wash away
the dark stuff, there's a seed or nut. if you crack it open, it looks
kinda like walnut flesh.

is this a walnut or related to walnuts? can it be eaten?

if it is edible, must it be cooked?