Jewel doesn't know that his father is the minister.
Jewel has always been the closest with his mother. He was closer with her because his mother loved him more. He was the product of a love affair between a minister and a townswoman. He didn't know that his father is actually the minister, but Darl does. Darl is the only one who knew besides Addie and the Minister.
Jewel gets mad at Cash for building Addie's coffin where she can see it.
When Jewel came home Cash was in the yard building Addie's coffin like she requested, which was not the problem. The problem was that Cash was building it right in front of Addie. This angered Jewel, it made him think that no one even cared about Addie or how she felt, but he didn't know that she didn't care or that it didn't upset her that Cash was doing this.
- Faulkner, William. As I Lay Dying: The Corrected Text. New York: Modern Library, 2000. Print.