What plant is that?

The September Mystery Plant is a large native shrub with opposite compound leaves and dome-shaped clusters of white flowers 3-10″ across at the tips of current season growth. Each 5-parted flower is only 1/4″ across, followed by a purplish-black berry that is great in pie or fermenting to a wine (however the raw berries are toxic!). This plant is common in roadside ditches and moist meadows or woodland edges – and is easiest to identify in bloom or in fruit.