Can you provide a detailed account of the events involving Boss Dharamsee and the grapes at the Shirdi mosque?

Certainly. According to Chapter 35, Kaka brought grapes with seeds as an offering to Sai Baba. When Baba began distributing them, he offered some to Boss Dharamsee, who was visiting with a curious but doubtful mind. Dharamsee disliked this variety and was hesitant, especially since they were unwashed. He ate a few but thought to himself, 'If he is a saint, how does he not know That I do not like these grapes?' In response to this thought, Baba gave him even more. Troubled, Dharamsee held them until Baba commanded him to eat. Upon obeying, he was astonished to find they were all seedless, a discovery that vanquished his ego and filled him with love for Sai.