Good point.It's a federal crime to take wild mallards unless you are a licensed wildlife rehabilitation.
https://en.wikipedia.org/wiki/Migratory_Bird_Treaty_Act_of_1918#:~:text=The Migratory Bird Treaty Act,MBTA), codified at 16 U.S.C.&text=The statute makes it unlawful,listed therein as migratory birds.
That said you might want to calm down on telling people you took WILD mallards and just say you have some mallards.