Can anyone identify this herb for me please?

Certainly looks like Nigella to me. It's likely to have a blue flower (very pretty) although it does come in white and pink.

It's generally grown for its pretty flowers but the seeds are edible. There are mainly two types, Nigella damascena and Nigella sativa (which is the one you would normally buy as the seed for eating).

 

I don't really know as I don't buy herb seeds but I wouldn't have thought so.

I have used the Nigella sativa in cooking Indian food. They refer to it as Kalonji. You sometimes see the seeds in Nan bread but it's used in cooking curries as well. It's normal to dry roast them first. Just toss them around, very briefly, in a heavy bottomed frying pan to release the aromatic oils. Similar to dry roasting cumin seeds.