In Bud, Not Buddy, what did Bud receive for the first time at the Sleets?
When Bud finds himself enjoying the hospitality of the Sleet family, he is amazed at their generosity and how they give him so much. In particular, what he is absolutely delighted about is the fact that Mrs Sleet has left him some new clothes on the bed. What he is particularly delighted about is that she gives him his very first pair of trousers. Note how his excitement is conveyed in the following exclamatory phrase:
Man, my first pair of trousers!
Even though the new clothes, according to Bud, are a "little too big," he is absolutely delighted with them and is really pleased. Clearly, compared to the Amos family, where he started off in this novel, the Sleet family are completely different in their love and generosity, and Bud is shown to benefit from this massively.