thimbleberry
noun
thim·ble·ber·ry ˈthim-bəl-ˌber-ē 
: any of several American raspberries or blackberries (especially Rubus occidentalis, R. parviflorus, and R. odoratus) having thimble-shaped fruit
Example Sentences
Recent Examples on the Web Trees and shrubs that provide fruits such as Indian plum, thimbleberry, bitter cherry, huckleberry and Oregon grape are good choices. 
oregonlive, 8 Mar. 2021 Michigan’s Upper Peninsula fully embraces the thimbleberry. Rebecca Powers, Washington Post, 13 Aug. 2019 Among those luxuries is the thimbleberry, named for its thimble shape. Rebecca Powers, Washington Post, 13 Aug. 2019
oregonlive, 8 Mar. 2021 Michigan’s Upper Peninsula fully embraces the thimbleberry. Rebecca Powers, Washington Post, 13 Aug. 2019 Among those luxuries is the thimbleberry, named for its thimble shape. Rebecca Powers, Washington Post, 13 Aug. 2019 Word History
First Known Use
1788, in the meaning defined above