From a 1988 article in the LA Times:
“The King has been taken care of for Saturday's Houston Oilers-New England Patriots game at Memphis. Houston Coach Jerry Glanville is leaving comp tickets for Presley at the will-call window. It's a truly beautiful gesture.” At the time, Glanville said “there will be a pass for him at will call, left under the name of 'The King...I hear Elvis is living now in Michigan or Minnesota. Well, we'd like him to come and be on our bench. I don't care how much weight he's gained. We still love him.”
He added that he was dead serious about leaving a ticket and was interested in seeing how many people (and what sort) show up to claim it.
In 2011, Glanville was asked by a NY Times reporters “there was a story that when you were coaching in the N.F.L., you would leave tickets for Elvis before every game. Was that true?” Glanville answered “Don’t screw up a good story with facts. We were playing the New England Patriots in a spring game. June Jones and I were riding to work in a pickup truck, and on the radio they said Elvis was spotted at a Burger King in Michigan. And June says, “Isn’t the halftime show dedicated to Elvis at our game?” I said, “Yeah.” He goes, “Well hell, we ought to leave him a ticket.” So we left him a ticket. Now if you get on the Internet, you’ll see that I left him a ticket for every game I coached in Atlanta. We never left a ticket for anyone in Atlanta, ever. But why ruin that story?”