The act of saying grace, typically done before meals, can also be done after meals.
This particular tradition pre-dates Christianity, and according to The Sacramentals of the Holy Catholic Church by Andrew Lambing, giving thanks after meals to God goes all the way back to Moses.
Moses, laying down the law for the chosen people, says: “When you have eaten, and are full, bless the Lord.”‘ According to the Talmud, the form of prayer recited by the Jews after each meal was this: “Blessed be you, O Lord, our God, the King of the world, who has produced this food (or drink) from the earth (or the vine).”
Early Christians adopted this practice, and over time it became common tradition among Catholic homes.
In particular, many homes would remember the faithful departed at the end of each meal.
Here is the most common Catholic version of saying grace after meals.
We give thee thanks, almighty God, for all your benefits, who lives and reigns forever and ever.
May the Lord grant us His peace. And life everlasting.
And may the souls of the faithful departed, through the mercy of God, rest in peace.
Amen.