excerpt from: allexperts.com (James Warner)
Elvis used the name John Burrows from roughly 1969 to 1977. Elvis may have gotten the name from a man actually named John Burroughs (HE was an essayist and naturist). I know that Elvis was an avid reader and had probably read some of Burroughs' work. Other names used by Elvis were:

John Carpenter (His character's name in CHANGE OF HABIT)
Sivle Nora (Elvis Aron / spelled backwards)
Alan (His codename at Graceland)


Nixon Meets Elvis
Elvis asks to be a soldier in the War on Drugs
excerpt from: About.com

Meeting and entertaining kings is one of the jobs of U.S. presidents. On one famous occasion, a U.S. president -- Richard Nixon, met the king of entertainment -- Elvis Presely. On December 21, 1970, three men got out of bed in rooms 505-506 & 507 of the Washington Hotel in Washington, D.C. where they had registered under the names of Jerry Schilling, Sonny West, and Jon Burrows.
Schilling and West were along for the ride, but Mr. Jon Burrows had a definite agenda -- and a pistol. Right after breakfast, the trio set out to visit the White House.
Three weeks earlier, Burrows had spoken in Palm Springs, CA with Spiro Agnew, the Vice President of the United States and had come away with a burning desire to fight the drug culture, hippies, the SDS, and the Blank Panthers.
Early that morning, Burrows simply walked up to the White House gates and handed the guard a 5-page letter addressed to President Richard Nixon. In his hand-written letter on American Airlines stationary, Burrows asked to meet with the President to give him a present and have the President appoint him "Federal Agent at Large" in the war against drugs. Was Mr. Burrows immediately hustled away by the Secret Service, never to be seen again? No. A few hours later, Mr. Burrows stood in the Oval Office of the White House speaking with the President Richard M. Nixon.
How could this have happened? "Mr. Jon Burrows," you see, was far better known by his kingly name -- Elvis Presley. During the brief Oval Office meeting, Elvis presented Nixon with a commemorative World War II-era Colt .45 pistol and told Nixon he felt the Beatles promoted an "anti-American" theme appealing to violence, drug use, dissent and protest. [See: Memo summarizing the meeting (National Archives)]
The Colt. 45 pistol is now on display at the Richard Nixon Library and Birthplace in Yorba Linda, CA.

Complete Text of Elvis' Letter to President Nixon

Dear Mr. President.
First, I would like to introduce myself. I am Elvis Presley and admire you and have great respect for your office. I talked to Vice President Agnew in Palm Springs three weeks ago and expressed my concern for our country. The drug culture, the hippie elements, the SDS, Black Panthers, etc. do NOT consider me as their enemy or as they call it The Establishment. I call it America and I love it. Sir, I can and will be of any service that I can to help The Country out. I have no concern or Motives other than helping the country out.
So I wish not to be given a title or an appointed position. I can and will do more good if I were made a Federal Agent at Large and I will help out by doing it my way through my communications with people of all ages. First and foremost, I am an entertainer, but all I need is the Federal credentials. I am on this plane with Senator George Murphy and we have been discussing the problems that our country is faced with.
Sir, I am staying at the Washington Hotel, Room 505-506-507. I have two men who work with me by the name of Jerry Schilling and Sonny West. I am registered under the name of Jon Burrows. I will be here for as long as long as it takes to get the credentials of a Federal Agent. I have done an in-depth study of drug abuse and Communist brainwashing techniques and I am right in the middle of the whole thing where I can and will do the most good.
I am Glad to help just so long as it is kept very Private. You can have your staff or whomever call me anytime today,
tonight, or tomorrow. I was nominated this coming year one of America's Ten Most Outstanding Young Men. That will be in January 18 in my home town of Memphis, Tennessee. I am sending you the short autobiography about myself so you can better understand this approach. I would love to meet you just to say hello if you're not too busy.

Respectfully,
Elvis Presley

P. S. I believe that you, Sir, were one of the Top Ten Outstanding Men of America also. I have a personal gift for you which I would like to present to you and you can accept it or I will keep it for you until you can take it.