The women, who were on a shopping trip in Charleston, South Carolina, returned home to Statesboro, Georgia, and gave the Lego to a young child.
They realised something was seriously wrong when the child opened the box and found a package of meth instead of Lego.
The quantity of methamphetamine had an estimated street value of US$40,000 (NZ$60,790). Although the women were unaware of the concealment, they had unwittingly committed a felony by transporting the disguised drug.