What should be placed in the base of the pole flying the American flag?

Hello,
according to the U.S. Flag Code ( http://suvcw.org/flag.htm ) there
doesn't seem to be any requirement to put something at the base of the
pole.
There are plenty of other requirements of can and can't do's,
but nothing related to placement at the base of the pole.

Apart perhaps from Section 10.
"Sec. 10. - Modification of rules and customs by President 

Any rule or custom pertaining to the display of the flag of the United
States of America, set forth herein, may be altered, modified, or
repealed, or additional rules with respect thereto may be prescribed,
by the Commander in Chief of the Armed Forces of the United States,
whenever he deems it to be appropriate or desirable; and any such
alteration or additional rule shall be set forth in a proclamation."
When the President can change the rules.

Search Strategy:
What should be placed in the base of the pole flying the American flag
://www.google.com/search?hl=en&ie=ISO-8859-1&q=What+should+be+placed+in+the+base+of+the+pole+flying+the+American+flag

I hope that is a satisfactory answer with reference to the U.S. Flag
Code.
If not, I will try to clarify the answer.
kind regards
lot-ga

On a page of supposedly factual trivia related to military service, I
found this bit of information:

"At the base of each flagpole on an official government installation
is a box buried in concrete. The box contains one saber, a .38 caliber
pistol and a book of matches. In the event the enemy overtakes the
last government installation, the survivor is to defend the flag with
the saber and pistol and burn the flag with the matches so that the
enemy cannot capture the flag."

"A collection of little known facts about military service"
http://www.2ndarmoredhellonwheels.com/itsafact.html