"I would give you some violets, but they withered all when my father died." (4.5.182-184).
Violets symbolize faithfulness. I believe at this point, Ophelia believes that her father was the only good, faithful man in the kingdom. I also feel she might be thinking about Claudius and Gertrude while saying this because of what she said earlier regarding the rue flower. This shows she is disgusted by their relationship.