I've never found anyone else who played Green Gravel. It must have been a very local game.   I don't remember any boys ever playing it. We girls held hands in a circle, faced inward, and walked to the left. We sang a lilting song that went like this:

Green gravel, green gravel, The grass is so green,

All over creation, I'm 'shamed to be seen.

Oh, Betty, Oh, Betty, Your true love is dead.

He wrote you a letter, To turn back your head.

The girl mentioned would turn around in the circle and still holding hands, walk with her back to the rest of the girls, facing outward. We continued (if recess lasted long enough) until each girl's name was called.

As I look back, it was rather a gloomy game.