When I was a child, I avoided this flower like plague, especially pulling it. It would leave yellow stains on my hand that would stay there for long. It used to grow all over the place in late spring and summer, including in crevasses of asphalt and stone, and in cracks at the corner of the house. In my village, nobody made anything out of the Rostopasca, it was considered a weed. My grandmother always told me to avoid it, as it is toxic.
It turns out my grandmother was right, but I also later found out it can also be a medicinal plant if the yellow latex it leaves when pulled is used in the right amount.
People dry out the stems and flowers and then make tea out of them, for internal and external uses. I have never used it, so I cannot attest to it.
Scientific name: Chelidonium majus