This is a plant that according to all the guides is extremely common, but it's one I don't find that often, though this year seems to be a better year than normal for it.
It's got a very small cruciform yellow flower, very distinctive and actually quite pretty
the stalk is tall, over 2 feet, and with a number of flower heads and unusually distinctive leaves
you can see what I mean, it's hard to confuse this with any other plant.
The flower heads and leaves are edible, and it's got, well to me anyway, quite a strong wasabi sort of kick to it.. some plants tend to be quite strong others not so much so best to try a few till you get one that suits your palate.