The black-and-white photo
The black-and-white photo Mathew finds in his great-grandmother's belongings symbolizes the dark past. The picture gives a hint of suffering, oppression, and death. When Mathew asks his great-grandmother about the photo, she tells him it was taken in 1932, the worst time in history when millions of people died in Ukraine due to a horrendous famine. Great-grandmother lost several close family members and has kept that secret from the rest of her family that survived the famine.
The gold string
Gold is a valuable commodity, and it symbolizes Helen's humanity. When Helen receives a letter from her cousins in Ukraine that they are starving due to a horrific famine, she sends them the most precious commodity and asks them to exchange it for food. Helen's action shows her concern for her fellow relatives starving in Ukraine.
Papa Stalin
Stalin is a symbol of oppression. Throughout the novel, the reader realizes that Stalin intends to rule forever and can do anything to oppress his competitors who challenge his rule. Stalin wanted to control the entire Soviet Union. When Stalin discovers a movement in Ukraine demanding independence, he engineers a famine that kills millions to disintegrate the freedom movement.