Compare Mar 8:6. On the occasion of feeding the five thousand, the multitude sat down on the grass (ἐπὶ τοὺς χότρους), Mat 14:19. It was then the month of flowers. Compare Mar 6:39, the green grass, and Joh 6:10, much grass. On the present occasion, several weeks later, the grass would be burnt up, so that they would sit on the ground.
Gave thanks
According to the Jewish ordinance, the head of the house was to speak the blessing only if he himself shared in the meal; yet if they who sat down to it were not merely guests, but his children or his household, then he might speak it, even if he himself did not partake.