Dear [Sender Name],

Thank you so much for the beautiful flowers you sent following the passing of my father. Your thoughtful gesture brought a small measure of comfort during this incredibly difficult time. The [Color] [Type of Flower, e.g., lilies, roses] were especially lovely, and they brightened our home during the visitation and service.

My father would have been so touched by your kindness. He always appreciated [mention a specific shared interest or memory related to the sender, if applicable, e.g., your visits, your sense of humor, your support]. Your thoughtfulness meant a great deal to me and my family. We are so grateful for your support and sympathy during this period of mourning.

With heartfelt thanks,

[Your Name]