Phytolacca americana, Pokeweed. Before the birds eat all of the highly poisonous (to humans) berries, does anyone want any seeds?
My grandmother enjoyed Poke Salad, as she called it.
Related Halloween story, almost. Yesterday I was doing a few outdoor chores while on the phone with one of our swap mates and I gathered a handful of the berries, staining my hand purple. A few minutes later, still on the phone, I passed a tangle of Sungold tomatoes. Yes, you guessed it. I plucked one delicious golden morsel with the offending purple stained hand and popped it in my mouth, as I always do when I walk by. After the call ended and I realized what I had done, I sat down and waited to die. Not this time, I guess.