what does it mean to have the united state commemorative seal on a famous artist picture?

Question

the picture is from august holland from the Fine art Gallery

Answer 1

It apparently means that he was commissioned to paint the work within certain guidelines - in other words, he didn't paint the work in hopes someone would buy it, he was told up front he would get a certain amount of money and what he painted would be accepted by the commissioner.
http://www.augustholland.com/