You gather things when you bring several of them to the same place. A gathering of friends is a group of friends getting together. The person in the picture has gathered a handful of berries.
Something glistens if it is softly shiny, particularly if it is wet. The cranberries in the picture are glistening.
You grind something by breaking parts of it off with friction. Metal or wood can be ground down by running a very rough surface over it, such as a grinding disc or sandpaper. Grinding will gradually change the shape of the thing being ground as the outer layer is removed.
You grind herbs and spices in a mortar and pestle by crushing them against the inside of the bowl.











