I have some named varieties of Beautyberry growing in my garden, but one shrub managed to appear by itself. It has now grown big enough to flower and set those stunning berries. I think it is a bird-planted seedling, but really I can't tell any difference between it and the ones I bought at the nursery. Same stunning, vivid purple berries.
I believe they grow from the berries it drops. I started off with one I dug up from the undeveloped land next door, and I have many now which I transplant to the marshfront behind the house.