I don't see Ultra Green Sweat Bees Agapostemon texanus often, but when I do spot them, they are quite a sight to behold. They are native to California, and nest in the soil, usually in bare, flat ground.
The female Ultra Green Sweat Bee in the Cosmos bipinnatus "Cupcakes White" blossom, above,
spent a long time in the blossoms of this plant.
A male Ultra Green Sweat Bee was lurking around, too.
Here you see it to the left, approaching the female bee in another Cupcakes White blossom
Here is the male Ultra Green Sweat Bee from another angle.