Thistle poppy

Argemone polyanthemos, also called a pricklepoppy or pricklypoppy.

A few of these have been popping up lately. The large delicate white flower with a bright yellow center flutters in the slightest breeze. Very prickly stem and leaves. "Argemone" is a herb referred to by the Greeks thousands of years ago. "Polyanthemos" means "many flowers".

A Native American traditional medicine plant with many uses, most notably as an anesthetic for surgery. They also ground the ripe seeds into an oily paste to apply to burns, sores, or cuts. Tea of seeds or the sap was used to treat sore eyes. ("argema" in Greek means cataract of the eye). Ripe seeds were pulverized & moistened, then rubbed into hair to kill head lice. Warmed root mash was applied to gums or inserted into tooth cavities to relieve toothaches.

According to the Lady Bird Johnson Wildflower Center, "The herbage of this poisonous plant is so prickly and distasteful that livestock avoid it."

The most interesting reference I found said this:
"The Hopi Indians used it to whip unruly children, an application that most of us would not approve of in the 21st century. But having collected a fair amount of prickly poppy, I can attest to how effective it would have been in that application!" Ouch!