This site lists primary sources on one side - and lesson plans on the other. Primary source images cover tribes by location and name as well as highlighting sources relating to Indian Schools, Art, Photography, Treaties, and Reservations.
The home page of the IDA is in process of re-building.
Check out the Indigenous Digital Archive's. Treaties Explorer: https://digitreaties.org
National Archives digitized thousands of Indian Treaties. Check them out by using the Treaties Explorer brought to you by the Museum of Indian Arts and Culture (MIAC). Some are difficult to read and understand, but there are maps and other visualizations to help explain the Treaties as they were created and changed through time. 
After Columbus: 400 years of Native American Portraiture
NATIVE AMERICAN HERITAGE MONTH
-check for activities, and dig into those to find prmary sources from all kinds of .gov agencies.