USA.gov's Federal Departments and Agencies
Sourcebook of United States Executive Agencies (Second Edition, 2018): https://www.acus.gov/publication/sourcebook-united-states-executive-agencies-second-edition (PDF, 188 p.)
Featured Executive Branch Publications:
https://www.govinfo.gov/collection/featured-executive-branch-publications?path=/GPO/
Executive branch org chart: Org chart
Cabinet agencies: http://www.whitehouse.gov/administration/cabinet
Commissions, Committees, Boards:
http://ucsd.libguides.com/c.php?g=410154&p=2803338
GovInfo. Featured Executive Executive Branch Publications