John Steinbeck’s Of Mice and Men is a depression-era story of two friends who are trying to make their way in the world without much education and just some blue-collar work experience. Most of the jobs that such people in this situation held were physically demanding, low-paying, and often temporary.
Early in the story they manage to get work at a ranch in Salinas, California. The title of their low-level job was “bucker,” which means one who carries, lifts, or shovels. In their case, they were “bucking barley” that was grown on the ranch.
The position held by Candy was that of “swamper.” In that setting a swamper was someone who maintained a specific area. Candy, due to an arm injury sustained in a work-related accident, could no longer be a bucker, so he kept up the bunkhouse for the other workers.
Crooks, the disabled African-American character, was the “stable hand.” He worked in the stable taking care of the horses.
Slim held a somewhat higher-level job known as “jerk line skinner.” This was the man who drove the mule team used to move heavy loads. Apparently the job was more difficult than it sounds because it earned Slim a great deal of respect among the other men on the ranch.
Any of these workers might also be referred to using the more generic term of “ranch hand.”