Here is the completed dialogue:
Caroline: Hello, Nelly. What an interesting book I've just read.
Nelly: Really? What is it about?
Caroline: It is about flowers. Do you know that there is a special flower for each month?
Nelly: No, I didn’t know that. What is the flower for my month?
Caroline: Oh. It’s the primrose. Do you know anything special about these flowers?
Nelly: Yes, I think they symbolize youth and new beginnings.
Caroline: And when were you born? I wonder what flower is for the month of your birthday.
Nelly: I was born in May.
Caroline: Oh, then it’s the lily of the valley!