This is the unripe berries of the dogwood. There are many types of this plant, but maybe it's Сornus sanguinea.
Shrub up to 4 meters high, with a strongly branchy crown and a variety of color drooping shoots. There are a lot of such shrubs in our park.
In late August or early September corymbose inflorescences turn into clusters of blue-black berries the size of a pea. The fruit of dogwood is inedible.