Plum flowers (Prunus domestica).

A plum is a stone fruit tree in the genus Prunus. Plum trees are grown for their juicy, sweet fruits, suitable for eating fresh or making jam. Flowers of plum tree are white and grouped 1-5 together on short stems, and the fruit having a groove running down one side, and a smooth stone.

If you want more information about this flower, just search the plant's Latin name on Google: