1869 Shield, Eagle, and Flags 30c Ultramarine and Carmine
This pictorial shows an eagle over a shield flanked by flags. I do not own this stamp yet. It is here courtesy of the Wikimedia Commons.
Flags
2012 Justice Flag (Forever) Red, Blue, and Black
This stamp shows the United States flag.
2012 Freedom Flag (Forever) Red, Blue, and Black
This stamp shows the United States flag.
1976 Plane, Globes, and Flag 31c Red, Blue, and Black
This 31c airmail stamp shows two globes as part of a stylized plane and flag.
1981 Flag over Supreme Court 20c Black, Dark Blue, and Red Booklet
This is the booklet version of the flag over the Supreme Court Building stamp.