It almost surely is one of the umbilifferas. It could be a carrot gone to seed or a Queen Annes lace which is a wild type carrot. I don't know of any umbelliferas that aren't edible.
It does look like wild carrot but I dont think this plant flowers. Its a bushy green plant almost like a shrub. It was growing in an old duck roost. Partly in the shade.
I'm still undecided but its twin lives in the plant identification thread from 5/4/11. If you look up that thread from noobiechickenlady it will give you some possible suspects.