Mess is an archaic or colloquial term for a portion, or serving, of food. The miltary still uses this term-as in Mess Hall. Joseph sent "portions" from his own table to his brothers, who could not sit with him because of his station as next to Pharaoh (Genesis 43:34). When David told Uriah to go to his home, "there followed him a present from the king"—there is no indication in the Hebrew that it was "a mess of meat," as the KJV has it (2 Samuel 11:8).
The Hebrew word in these two cases is the one which is translated "gifts" in the account of the great banquet given by King Ahasuerus to celebrate the coronation of Queen Esther (2:18). It is an interesting fact that the well-worn phrase "a mess of pottage" does not appear in the Biblical account of Esau's sale of his birthright (Genesis 25:29-34) or in the reference to it in Hebrews 12:16.
(The Bible Word Book, Bridges & Weigle pg 223)