Peasants were typically limited in picking clothing because they did not have much money. In what they could afford, peasants would only have about one to two outfits to wear for many years. Even worse, the nobility would limit what the peasants could wear; however, this did not bother the peasants because they could not afford to purchase much anyway.
In what they could buy, peasants would often resort to wearing "tunics" which were often made out of wool. Men and women would modify tunics by cutting slits for places such as the head, arms, and legs. Men would often let the tunics fall just past their knees while women would let the tunics fall down to their legs which can be thought of as dresses.
As for undergarments, it wasn't until the 14th century that peasants began to wear "shifts." Shifts were not as baggy as tunics and would often be longer than the tunics themselves. As a result, shifts hugged the body more closely and provided more comfort against the abrasive feel of wool. As for underwear, it is thought that men wore loin cloths while it is uncertain if women wore any kind of underwear.
So what about headwear? Women usually wore a type of linen veil that would often cover their hair and would be kept in place by a ribbon or a bow while men would wear various types of hats. These included straw hats to more elaborate such as leather coverings. Others might as also worn felt caps that would fasten around their necks.
In terms of footwear, many went without shoes in warmer seasons; however, the common footwear was leather shoes which were end together by straps. These shoes may have also had wooden soles for support. Besides leather, felt could have been also used. To support footwear, it is also possible that men would wear hose because of their shorter tunics while women probably didn't wear hose because their tunics reached all the way down to their feet.