Credo che pane rustico sia l'espressione più adatta in questo contesto.. ma è solo la mia opinione, nessuna delle espressioni citate è sicuramente sbagliata.E' plausibile, seppur sia difficile dirlo, l' espressione e' altamente context-specific e, pertanto, difficilmente comparabile.
Peasant bread potrebbe essere pane campagnolo, pane semplice, pane rustico...
Peasant foods are those dishes specific to a particular culture made from accessible and inexpensive ingredients and usually prepared and spiced to make them more palatable. They have often formed a significant part of the diets of those who may live in economic (but not necessarily cultural) poverty compared to the average for their society or country. Peasant foods are so called as being the diet of peasants, that is, tenant or poorer farmers and their farm workers, and by extension, of other cash-poor people. They may use ingredients, such as offal and less-tender cuts of meat, which are not as marketable as a cash crop. Characteristic recipes often consist of hearty one-dish meals, in which chunks of meat and various vegetables are eaten in a savory broth, with bread or other staple food.