Its pretty much all edible, but older stems are fibrous - so best chopped and cooked, the bulbs are like a cross between a spring onion and garlic clove - okay grated or sliced and cooked. The little flower bulbuls are edible too raw or cooked.
(Legal rider: It is of course illegal to uproot plants without landowners consent)
(Legal rider: It is of course illegal to uproot plants without landowners consent)