I don't remember when I heard/did this, but sometime in my life, I remember picking these 'heads' with a long stem. Then hold the stem up close by this head, take the long stem and wrap it around the head, and pull it and as this is done say, "Mama had a baby and it's head popped off." The way it is held results in the seed head popping off when you wrap and pull the stem end around it.
I didn't know what this plant was...I don't remember calling it anything as a kid...but in looking I found that it can be called a narrow leafed plantain, and is also know as ribwort or buckthorn.
But what I would like to know is who thought up those lines to say with that action? Have you heard it before? I just think they are such strange lines to say....and I hate to admit it, but showed Lorelei.