It self seeds and has done for years in my garden and I handle it, so its no more poisonous then any other garden plants I would say.

No - I'm sure it isn't. But would you want to eat it anyway? Let's make sure we're talking about the same plant - Nigella damascena.

Being in the Buttercup family which includes Monkshood and Delphinium, both of which are toxic this genus however seems to be an exception with of course one species (the name of which escapes me) being the Nigella seeds used to cover very posh bread buns.

Nigella sativa :-)