Hypericum perforatum, Saint Johns Wort

Saint Johns Wort Family, Hypericaceae.

Some species of this family are native to North America, but this one is
alien, a native of Europe; weedy, invades pastures, toxic to livestock.

This species is generally referred to as Klamath Weed in the western US.

Black dots on petals are translucent oil glands, appear to be perforations.