Storing $1,000,000 of treasure

Via Weather Sealed, here's a handy chart of how much space $1,000,000 worth of various goods takes up, the best subterranean hiding place, and the, er, risks associated with each.
Stuff That You Might Put In Your Hole

Material	Value Per Pound	Size Of $1,000,000	Bury In	Pros	Cons
Wheat	$0.09	190,000 bushels	subterranean silo	never hungry	bulky, mildew, mice, locusts
Moonshine	$0.13	160,000 7gal stills	corked clay jugs	many lovely banjo solos	blindness
Gasoline	$0.49	320,000 gallons	underground tank	Peak Oil, baby!	fumes, third degree burns
Ammo	$2.10	525,000 shells	surplus ammo cans	gun owners need you	you need owners with matching gun
Vodka	$7.80	1,800,000 shots	Russian-proof bear boxes	the Bloody Mary	requires V8 and Worcestershire
Jerky	$18	27 tons	duct-taped lawn bags	infinite lifespan	everything stinks like jerky
Cigarettes	$57	7 pallets	basement of abandoned 7-11	captive market	nicotine stains
Guns	$60	2,500 shotguns	water-tight firearm lockers	reinforces Alpha Dog image	ATF raids, terrorism indictment
Silver	$270	3,700 pounds	rolling plastic totes	Werewolves begone!	not Gold
Caviar	$2,400	1,100 servings	Arctic tundra	endear yourself to power elite	must ice or eat within 3 hours
CPUs	$6,000	4,000 chips	sealed anti-static tray	light weight, inert, brainy	loses half of value every two years
Cocaine	$9,000	50 kilos	legs of faux llama keepsakes	world-wide demand	unstable customers, Scarface
Gold	$16,500	275 bars, 100g each	treasure chest	time-tested currency	metal detectors, confiscation
$100 Bills	$45,000	43? stack	mason jars	backed by U.S. Government	worthless beyond Thunderdome
Diamonds	$175,000	black velvet pouchfull	vault with lasers and trip wires	profit, intrigue, girl’s best friend	low utility, De Beers assassins
Plutonium	$2,000,000	1.3 inch sphere	argon-filled, lead-lined bunker	ultra-compact	CIA, critical mass, death by inhalation