The only mention i can find of a VC at Arlington is from this wiki Link
The World War I Unknown lay in state in the Capitol Rotunda from his arrival in the United States until Armistice Day, 1921. On November 11, 1921, President Warren G. Harding officiated at the interment ceremonies at the Memorial Amphitheater at Arlington National Cemetery. During the ceremony, the World War I Unknown was awarded the Victoria Cross by Admiral of the Fleet Lord Beatty, on behalf of King George V of the United Kingdom.[13] (The United Kingdom Victoria Cross was placed with the soldier. Earlier, on March 4, 1921, the British Unknown Warrior was conferred the U.S. Medal of Honor by General of the Armies John Pershing.) In 1928, the Unknown Soldier was presented the Silver Buffalo Award for distinguished service to America's youth by the Boy Scouts of America.[14]
I highlighted here that it says the Cross was placed with the soldier. Which i assume was buried with the soldier?
Additionally: Are all the medals in Arlington ceremonial or have they been awarded for some other reason?
EDIT: FOUND A PIC
The Victoria cross, is the greatest award for valor in the British military. It is considered to be the hardest medal to win, based on how long it has been around, and how few of them have been awarded.
The Victoria cross at Arlington was ceremoniously granted to the unknown soldier of the first world war by the British. The unknown soldier in Westminster Abbey in London was at about the same time granted a Medal of Honor.
The cenotaph in London was the site of the first unknown soldier, and at the time it was a really big ceremony. As an aside, you should look up the details of the ceremony in 1920, it's impressive. The american military presented the unknown soldier at the cenotaph a medal of honor. The Victoria cross was presented to the unknown soldier in Arlington a few months later.
See: The Victoria Cross, Peter Duckers.
The newly re-modeled display room, just opened a few days ago, does a much better job explaining all the awards and items presented to the unknowns, rather than just displaying them. Definitely check it out, even if you have been there before.