Rolling and romping in the grass

We were at the park a couple weekends ago and I was finally able to catch Newton on camera rolling around in the grass. I believe he's trying to get an itch on his back but I also think he is rubbing himself to pick up smells from the grass. Whatever it is it sure is funny. At the same time he's snorting and grumbling, probably another sign - a sign of content. All is well when Newton is on grass. On a side note, Newton is wearing a lei. Yes, my dog got lei'd har har.