Civilian labor units assigned to US military in Germany WW2

It's my understanding when Polish forced laborers were liberated in Germany, they were assigned to noncombatant civilian labor units under command of US military.  I had 3 uncles forcibly taken from home in Poland to forced agricultural labor in Germany.  They were designated as Displaced Persons when the war ended.  I have two later photos of them in what look like US military uniforms, taken before they emigrated to the US in 1947.  General googling on this subject has yielded copies of documents identifying for example "Labor Supervision Company US Army", and even "discharge" papers for individuals in these units.  Any information on this subject would be appreciated.