The narrator in The Yearling does his expected, normal job letting us see all of Jody's thoughts and emotions throughout the story while also giving us plenty of background on the characters and events in the Baxters' past. For the most part, the narrator only gives us direct insight into Jody's thoughts and feelings, though. We learn about Ma Baxter from the outside, but we never get to hear her side of the story.
The one exception to the narrator's focus on Jody is a quick trip into Penny's brain, just enough of a peek to find out some background info on why Penny treats Jody the way he does: "He thought, 'A boy ain't a boy for long.' As he looked back over the years, he himself had had no boyhood" (2.4-5).
Most of the time, though, we're left trying to figure out what the other characters are thinking. When Pa looks at the young deer "with an unfathomable expression" (30.29), we have to guess at Pa's thoughts right along with Jody.