One story from a flower shop.

While buying flowers for my mother, I overheard a young woman arguing with a florist about how much a bouquet costs her. She looked confused and tense, so I secretly paid the difference. When she found out about this, she sincerely thanked me, explaining that the flowers were for her sick grandmother. A few months later, I accidentally met her at the same flower shop, she was with her family, and it was a pleasure to meet them all, and we've been friends ever since.