| Artist | Nationality | Dates |
|---|---|---|
| Unsigned, American | American | late 20th century |
| Unsigned, | French | 19th century |
| Unsigned, French, | French | early 20th century |
| Unsigned, Boston School | American | c. 1900s |
| Unsigned, American, | American | late 19th century |
| Urbain, John | American | 1920-2009 |