leave the umbelliferaceae alone unless you really really know what you're doing, the only time i'd ever recommend eating any members of the carrot family is if you've got them from a supermarket or grown them from seed yourself, ie carrots. avoid all the rest like the plague. hemlock water dropwort (to give it it's full name) is so easy to confuse with all sorts of things, for example cow parsley, and it's deadly (i believe it's the most poisonous native plant in the uk, someone will be along in a second to correct me on this though) really really deadly. if you make a mistake with the ID of something like cow parsley and end up eating hemlock water dropwort instead it's pretty unlikely that you'll ever make any mistakes again, at the very least you need to make sure that your life insurance is up to date before you start playing around with this family of plants.
have i over-emphasised this enough yet?
just to be on the safe side leave them alone or you will die!!!!!!!!!!!
having said all this, sweet cicely and rhubarb crumble is lovely
happy foraging
stuart