Hi there,
They have the look if Inkcaps -
Coprinus sp.
Some
Coprinus species are considered poisonous if eaten -certainly not by just handling or touching. - (Usual hygene rules should be applied before eating though, whenever fungi have been handled).
But is it realistically likely that these would be eaten? - Animals will tend to leave them alone, and how many children - of an age such that they'd be out on the streets unsupervised, would be likely to eat something found growing out of the tarmac?
I'd be more worried about the damage they are causing to the footpath.
They are very short lived, and will probably have all but disappeared within a couple of days, but if you are still concerned then you could pick them and dispose of them.
Regards,
Mike.