Self seeded in gutter of underpass - I think birds nearby often bring food over here, since I find a lot of seed pods that don't match anything in the immediate vicinity (namely Acacia pods and Allocasuarina luhmennii (?) pods)
To me, these look like juvenile phyllodes. I reckon maybe A.rubida or A.implexa, does not look like mature bipinnate foliage that would be case in the ID suggested