Tteok (also spelled ddeock, duk, dduk, ddeog, or thuck) is a Korean sweet cake made with glutinous rice flour (also known as sweet rice or chapssal) by steaming. There are hundreds of different kinds of Tteok eaten year round. In Korea it is customary to eat TteokGuk (Tteok soup). This particular shape of rice ovaletts are used for new year soup.
Read more from Wikipedia…

• Use:
  New Year Soup, Ingredient for main dish

• Storage:
  Keep in the freezer.

• Short Korean lesson: *^^*
  TteokGuk (떡국)=New Year Soup
  Tteok (떡)=Sticky Rice Cake