Good Job Bob! From prior research years ago the United States made it illegal to use Spanish currency as legal tender as of July 1, 1857. I do not know if that law also included Mexican currency? Some folks have found small denominations of Spanish silver ie one reales and two reales with metal detectors around old slave cabins indicating to me that slave owners may have given them to slaves after that date. I found a one reale dated 1763 myself back in the 1980's in Virginia and thought it odd at the time that it was next to slave quarters.
If Mexican currency was outlawed this could help explain why the former Alabama Confederates donated the coins to the ADAH after the war?