Raspberry (Rubus idaeus), fam. Rosaceae.
Quite abundant in the forest, but the overwhelming majority of the bushes give very low-grade crop – small berries, crumbling into separate grains at the attempt to gather them. Only a few exemplars (which possibly appear in the forest on someone's initiative) belong to a better sort.
Young leaves have astringent properties, and can be used to make tea.
In 2014, however, over a large area of the DVRZ forest raspberry (as well as dewberry, and stone bramble) gave unprecedented crop. Apparently, it was facilitated by favorable weather – a record wet May, then cool June-July (the berries ripened gradually and did not spoil a long while).