9:23 AM PT -- A rep for BWW told us ... "Buffalo Wild Wings takes food preparation, service and quality extremely seriously and we are looking into this situation. We’ve reached out to Jared Cook and our suppliers for more information."

Green Bay Packers tight end Jared Cook knows how Brad Pitt ﻿felt at the end of the movie "Seven" -- 'cause he opened up a box and found a decapitated head inside!!!

The 29-year-old says it all went down at Buffalo Wild Wings on Tuesday -- when he opened up his box of lemon pepper wings and saw a decapitated HEAD staring back at him.

"Tongue, eyes, and beak all present. With extra seasoning," Cook said.

When he raised the issue to staffer, Cook says he was told, "Sorry unfortunately this happens because the chicken is fresh."