Jim Monroe/Jerry Coffee
Don't know if this will help or not as there seems to be some references to "Washington County" and "Washington" Arkansas used interchangably in the family trail.
Washington County is in NW Arkansas with Fayetteville (home of the University of Arkansas--"Razorbacks") as its county seat. It is in the mountainous area of the Ozarks and while there may have been a "plantation" or two, for the most part it was home to the yoeman, single family farms common in most southern mountain areas (KY, TN, WV, NC, North GA and AL) and like them, a hot bed of Union sentiment during "the wah."
Washington, the town, which was also the temporary Confederate capitol after the Union occupied Little Rock is in SW Arkansas--Hempstead County, about 15 miles west of Hope...30 miles NE of Texarkana (just off I-30). It is among the oldest towns in the state and was on the old road to Spanish Texas. It is currently better known as "Old Washington State Park" a state historical park. A number of homes dating from the 1820s-30s have been reconstructed and furnished and open for tours to the public. The James Black smithy---where according legend Black forged the first Bowie knife for James Bowie today has the only known knife making school in the country. Also reconstructed, in addition to the old Confederate temporary capitol/original Hempstead County Courthouse, are a couple of taverns that supposedly hosted Sam Houston, Davy Crockett, Stephen F. Austin (and Bowie) among others during their travels in the 1820s-30s.
A "Washington" plantation would more likely have been in the latter site ("Old Washington") since it was more hospitable to plantation operations due to its geography, terrain and environment. They also have a large collection of early Arkansas records/geneology in the SW Arkansas archives in one of the old school buildings. In ancestor hunting for the "Washington" references, you might want to look at that for the location.....
Jack DuBose (a 5th generation Texan, transplanted to Arkansas)