I did a small search and I found below information:

United States - Federal
...Article III Section 3 delineates treason as follows:

1. Treason against the United States, shall consist only in levying War against them, or in adhering to their Enemies, giving them Aid and Comfort. No Person shall be convicted of Treason unless on the Testimony of two Witnesses to the same overt Act, or on Confession in open Court.
2. The Congress shall have Power to declare the Punishment of Treason, but no Attainder of Treason shall work Corruption of Blood, or Forfeiture except during the Life of the Person attainted.

United States
1. Martin James Monti, United States Army Air Forces pilot, convicted of treason for defecting to the Waffen SS in 1944.
2. William Bruce Mumford, convicted of treason and hanged in 1862 for tearing down a United States flag during the American Civil War.
3. Aaron Dwight Stevens, took part in John Brown's raid and was executed in 1860 for treason against Virginia.

Others in the US
1. Robert Henry Best, convicted of treason on April 16, 1948 and served a life sentence.
2. John Brown, convicted of treason in 1859 and executed for attempting to organize armed resistance to slavery.
3. Iva Toguri D'Aquino, convicted 1949.
4. Governor Thomas Dorr 1844, convicted of treason against the state of Rhode Island;
5. Mildred Gillars, also known as "Axis Sally", convicted of treason on March 8, 1949; served 12 years of a 10- to 30-year prison sentence.
6. Herbert Hans Haupt, convicted & executed of treason in 1942 after being named as a German spy
7. Tomoya Kawakita, sentenced to death for treason in 1952
8. Mary Surratt, Lewis Powell, David Herold, and George Atzerodt, all convicted by military tribunal and hanged on July 7, 1865 for treason and conspiracy related to the Lincoln assassination.
9. Philip Vigol and John Mitchell, convicted of treason and sentenced to hanging;