It took me a while to find this one - none of the usual sources told me of a trumpet shaped flower, with the ragged / toothed edge leaves. Until I had a brainstorm - and I was right. The first ones I looked at were Convolvulus, which goes by the common names of Bindweed or Morning Glory. They come in various shapes and sizes, but none of them have this type of leaf. I then though of Jimson Weed. This is poisonous, especially to livestock. It's related to Datura, or the Devils Trumpet, which people grow as an ornamental.