Actually, the poor whites of the time resented the plantation system. The slaves undercut the job prospects for poor whites and undercut their wages when the workforce was part slave and part free. And poor farmers could not compete with the big plantations, so their earnings stayed at a subsistence level.
To add injury to injury, the Confederate draft forced white men into the Confederate Army — except that owners of twenty or more slaves, and in some cases their brothers, were exempt from service. And anyone who could afford the going rate could hire a substitute to fight in his place. The Confederate soldiers coined the phrase” “A rich man’s war but a poor man’s fight.”
In the hills and in the mountain country, the war was very unpopular. “Jones County” aka “the free state of Jones” was the most famous center of resistance, (and let’s not forget West Virginia) but there were many remote places in the South where the men sat out the war.
After the war, poor whites and freed slaves were on a near equal footing under the sharecropper system. In the early 1890s, two farmer organizations, the National Farmers Alliance and the Colored Farmers Alliance joined forces to create the Populist Party as a force against the Democrats and Republicans.
The Populists elected some Congressmen and Governors in 1892. The Jim Crow laws and the systematic disenfranchisement of black voters (who had been voting since the 15th Amendment had passed) were a reaction to Populism and the means by which the Democrats smashed the Populist Party and formed the one-party South.