To dream of the yam could mean that you are feeling hungry during your sleep. The yam is also a symbol of nourishment the dreamer gives to himself. The yam could also indicate the special day of the year you are celebrating.
Dream dictionary: Yam dream meanings
Dreaming of yam represents your memories of family reunions or celebrations.
If you see yams in the dream, then they show that you are longing for family celebrations. Your unconscious sends you a sign that your connection is broken with the most important peoples in your life.