We did a shot like this once. We used one of those rubbery thick "fake lawns" and hung it between two saw horses. Then we cut a cross shape in the center that would accommodate the torso of the actor. Then we poured sand over the grass so it looked like he was submerged in grass. (there was quite a bit of spillage so throw a tarp down). The first time we did it, we didn't have near enough sand, and the grass would eventually show through as he "sank" into the sand.
We did a shot like this once. We used one of those rubbery thick "fake lawns" and hung it between two saw horses. Then we cut a cross shape in the center that would accommodate the torso of the actor. Then we poured sand over the grass so it looked like he was submerged in grass. (there was quite a bit of spillage so throw a tarp down). The first time we did it, we didn't have near enough sand, and the grass would eventually show through as he "sank" into the sand.