Dear Tommy:

You wrote:

Dear Sir:

This is from Dragon Seed by Pearl S. Buck (page 18).

“Sell it,” she had said. “It will buy me a pair of earrings.”
“Do you want earrings?” he had asked her in surprise. “But your ears are not pierced.”
“I can pierce them,” she had said.
“I will buy you the earrings,” he had answered her, “but not with your own hair.”

Question 1: Why did the author use the past perfect form (she had said or he had asked)?

Question 2: How would the meaning change if the author used the simple past form (she said or he asked)?

Sincerely,
T

I am sorry that I cannot answer your question completely. I do not currently have a copy of Dragon Seed at my disposal (my family donated its copy to the local library).

The use of the past perfect depends on the context. The past perfect is used to indicate an action that took place or a condition that existed before the time used by the past tense. Probably the novel is describing an action in the past (most novels do), but this conversation took place before the main action being described. It could be part of a flashback, for example, or a reminiscence.

If the writer used the simple past tense, that would indicate that the conversation took place at or around the same time as the rest of the action being described.

Although I do not have the context available, I suspect a character is reminiscing–recalling how she got the earrings which she is now wearing or using. Her use of the earrings would be in the past tense, but her remembering about how she first got them would be in the past perfect since that action took place some time before the time being described in the story.

For a bit more on this, see the Grammar Slammer glossary on Perfect Tenses (also https://www.englishplus.com/grammar/00000361.htm) and Tense of Verbs (https://www.englishplus.com/grammar/00000378.htm).