Then, depending on which meal, and which Buddhist tradition, some verses like this (called a "gatha") are recited, and, ideally, reflected upon.
Seventy-two labors brought us this food, we should know how it comes to us.
We should consider whether our virtue and practice deserve it.
As we desire a natural harmony of mind, we should be free from greed.
We take this food to support our life
and to attain the Way.
First, this food is for Buddha, the Buddha's path, and the Buddha's community.
Second, it is for our teachers, parents, nation, and all sentient beings.
Third, it is for all beings in the six worlds.
Thus we eat this food with everyone
We eat to stop evil
To practice good
To save all sentient beings
And to accomplish our path.
I don't recite these verses aloud at Thanksgiving, because of the diversity of people we have over--I wouldn't want anyone to feel the discomfort I used to feel at elaborate mealtime prayers at the houses of people who were devout in a way I was not--but I silently go through this little series of thoughts. It's kind of like reflecting on a rosary.
And, very usefully, it encourages moderation in eating.