Dear [Recipient], I am writing to you to express my sincere gratitude for the generous gift you gave me for my birthday. I was so surprised and delighted to receive such a thoughtful present. Your gift was so thoughtful and generous. I am so grateful for your thoughtfulness and kindness. I will treasure it for many years to come. Thank you again for your generous gift. I am so lucky to have such a kind and thoughtful friend. Sincerely, [Your Name]