i forgot to remember to forget / mystery train

The Hillbilly Cat had his first number one hit with his last single for Sun Records. Stan Kesler and Charlie Feathers wrote 'I Forgot To Remember To Forget' in the classic rockabilly style; but Elvis thought it sounded too country. When they brought in drummer Johnny Bernero, he changed his mind. It spent five weeks on the top of the country chart.  It was released with the classic 'Mystery Train' as the B-side. 

http://www.elvis.com/

'Mystery Train' was written by Junior Parker and Sun Records founder Sam Phillips and peaked at number eleven on the country chart. They were inspired by the Carter Family's 'Worried Man Blues'. It features Scotty Moore on lead guitar, Bill Black on bass, and Presley on vocals and rhythm guitar.

https://www.youtube.com/watch?v=Q_eE0NPArEY