Honrore Daumier, The Third-Class Carriage, 1862.

This is an important piece because it not only shows the working class people, but puts you in the same part of the carriage, thus making the viewer a working class individual.  Tells the tail of the hard life of labor where noone is exempt, from the nursing mother to the elderly, and even children.

Gustave Courbet - The Stonebreakers - 1850

Machine like, pitable, giving history painting status to an action as mundane as stonebreaking.  Clothing clearly shows the hardness of the lifestyle and work.  

Gustave Courbet - A Burial at Ornans -  1849

*Giving importance to mundane topics by paiting them in a large scale.  Showing "ugly" people, in the mode of dress, etc (defended by Baudelaire as being no more ugly than that of Paris, just a different kind of ugly.  That is what they look like.)  Ruddy faces of the beedle- implies drunkeness.