Can you tell me the story about Boss Dharamsee's first visit to Shirdi and the miracle with the grapes?

Certainly. As recounted in Chapter 35, a man named Boss Dharamsee visited Shirdi with a curious but doubtful mind. During his darshan, another devotee, Kaka, offered Baba grapes that had seeds. Baba began distributing them, offering some to Dharamsee. Internally, Dharamsee was troubled because he disliked seeded grapes and was also concerned about eating them unwashed. He even questioned Baba's sainthood in his mind for not knowing his preference. Sensing his conflict, Baba commanded him to eat the grapes. Upon obeying, Dharamsee was astonished to find they were perfectly seedless. This miracle completely shattered his skepticism, and as the text says, 'All his ego dropped away, and love for the saint was born.'