Well first off to correct your lack of knowlege on the subject there is no "expired shelf life" on munitions.
Yes we have found actual weapons.
To date the Polish troops have recovered over 100 shells filled with mustard gas.
There have been other more "quiet" take downs of weapons and the people who were making them.
That last "public" incident was the 155mm shell filled with 4 liters of sarin that was uned in an I.E.D.
I have personal knowledge of soldiers in the desert digging out weapons from the desert with quantities of MIXABLE chemicals alongside the munitions....
And that it was done clandestinely and never reported.