I know most people know that Elvis was at G. Rollie White in 1955, about a year before he went on Ed Sullivan - I did not attend as my parents weren't even married back then:

From Reddit, citing Sun Records archives:
There was a 7:30 p.m. concert in College Station at the G. Rollie White Coliseum on the campus of Texas A&M University in Bryan, Texas. The show was sponsored by the Office of Student Activities. Advance tickets cost 35-cents for children and 75-cents for adults. At the show, seats were 50-cents and $1.00. Elvis was dressed in a pink dinner jacket, black open-collar shirt, pink socks, and red shoes
When Elvis rolled onto campus that evening of October 3, the Aggie footballers couldn't believe their eyes, much less their ears, as hundreds of squealing girls wiggled and cavorted like Elvis himself. The girls had gone gaga over the man on stage. Some pulled their shirts mid-high, seeking approval, while others went further, removing their panties and throwing them onto the stage.
Elvis needed to look no farther than the front row to know it wasn't a normal college crowd. There stood military officers, sabers on their hips, shoulders-to-shoulder facing raucous fans. No one had ever seen anything like it at A&M. But, for the most part, the kids seemed to be having fun, until Elvis did the unthinkable. He spit his gum onto the stage floor.
In the blink of an eye, the crowd rushed to the edge of the stage. Corps members moved in waves, shoving their dates aside. They shook their fists and cursed the swivel-hipped rocker. ''You desecrated our stage''! they screamed. ''Somebody knock that sonofa***** off of there''. Swords were suddenly drawn. A company commander grabbed the microphone and began barking orders; 'Men, get back to your seats'! This boy didn't mean any harm. We've already picked up his gum. Everybody get back. Now, goddammit''.
Amazing, the cadets retreated. Elvis held his arms above his head and apologetically smiled. 'Sirs and ladies', he said, 'I'd like to say I didn't mean anything by it. I'll try to do better'. With those two strings still dangling from his guitar, Elvis went into ''Shake, Rattle And Roll'', a song made famous by Bill Haley and the Comets. Even the cadets started moving to the music. By the time he tried ''Good Rockin' Tonight'', the audience was his once more. He even returned for encores, including ''Maybellene'', a song made famous by Chuck Berry.
The Battalion mentions the Louisiana Hayride here Monday on Sept. 29, 1955 mentioning that Elvis was part of the
Louisiana Hayride music program.
It cracks me up to see his 1954 &
1955 tour - I wonder what some of those Texas towns were like in 1955...