They found them all over the nation for decades. Even the government of Iraq turned over two bunkers of the stuff to the UN when they signed the Even the New York Times reported in 2014 that they had discovered almost 5,000 munitions in Iraq after the war ended.
And in 2009 when Iraq joined the Chemical Weapon Convention, they turned over 2 bunkers full of the stuff to the UN as well as production facilities.
web.archive.org
Heck, just look at WIkileaks. A ton of the stuff released there was about the discovery of Iraqi chemical weapons.
Buried in the WikiLeaks avalanche of documents related to the war in Iraq are various reports about the discovery of chemical weapons caches inside Iraq—reports which contradict the revisionist narrative about the genesis of the war.
www.heritage.org
By late 2003, even the Bush White House’s staunchest defenders were starting to give up on the idea that there were weapons of mass destruction in Iraq. But WikiLeaks’ newly-released Iraq war documents reveal that for years afterward, U.S. troops continued to find chemical weapons labs...
www.wired.com
I love how many people keep repeating that lie, especially when it is so easily proven by multiple sources to be a lie.