The Richard Fields in Jefferson TX and traveling to Richmond is likely Capt Richard Fields of the 1st Cherokee Mtd Rifles (Drew's). He would have been 61 or so and his family was probably living in north Texas as refugees. (This is my ggg grandmother's older brother).
The Capt Richard Fields of Watie's Regt was 39 yrs old at enlistment. I assume he is the "Dick Fields" that killed Andy Nave (if remember the name right) at Park Hill per a letter from Watie to his wife who spent much of the war in north Texas.
There is also a "Rich Fields" shown as "surgeon's interpreter", age 38, on Watie's roster.
There are several "Richard Fields" in Cherokee rolls and Emmett Starr's genealogy charts that would have been living during the time of the war but I don't have their birth/death dates to aid with identification.
I'll have a Fields cousin in Delaware district that may be able to unravel this for us.