These teeth sometimes form a regular fringe round the margin, and the petal becomes fimbriated, as in the pink; or laciniated, as in Lychnis Flos-cuculi; or crested, as in Polygala.
It is almost certainly the common milkwort, Polygala vulgaris.
Milkwort (Polygala) - The hardy Milkworts are neat dwarf plants, with flowers much resembling those of the Pea family.
Changes are produced in the whorl of stamens by cohesion of the filaments to a greater or less extent, while the anthers remain free; thus, all the filaments of the androecium may unite, forming a tube round the pistil, or a central bundle when the pistil is abortive, the stamens becoming monadelphous, as occurs in plants of the Mallow tribe; or they may be arranged in two bundles, the stamens being diadelphous, as in Polygala, Fumaria and Pea; in this case the bundles may be equal or unequal.