Or to put it in somewhat more general and less loaded terms, saying grace.
I grew up in a UU household, and although we said a grace at dinner, it was not a prayer, since we did not believe in any gods. There was no referent for "you" in "thank you for this food"; rather, it's a general expression of gratitude and acknowledgment of the work that brought the food to our table, and the lives sacrificed in doing so. (Perhaps "we give thanks for this food" would have made more sense.)
Saying grace is similar in many ways to giving a toast, which might be worth further exploration.
That's the inverse of how I understand those terms and how loaded they are. “Prayer” is a nearly universal religious practice even in ones that are not especially theistic, whereas “grace” is a distinctly Christian notion.
I grew up in a UU household, and although we said a grace at dinner, it was not a prayer, since we did not believe in any gods. There was no referent for "you" in "thank you for this food"; rather, it's a general expression of gratitude and acknowledgment of the work that brought the food to our table, and the lives sacrificed in doing so. (Perhaps "we give thanks for this food" would have made more sense.)
Saying grace is similar in many ways to giving a toast, which might be worth further exploration.