Which character in A Jury of Her Peers hides the small box in her coat pocket, as to not give away the fact that the main character had a motive for murder?

In Susan Glaspell’s story “A Jury of Her Peers” (adapted from her play “Trifles”), it is Martha Hale who puts the box in her coat pocket. The box contains the dead canary, which both Mrs. Hale and Mrs. Peters have come to believe John Wright had killed. They see this killing as an inciting factor that probably led Minnie Wright to kill her husband.
It is not concrete evidence, and Mrs. Peters tries to joke about them “getting all stirred up” over the dead bird. Nevertheless, they believe that the sheriff might understand the logic they had worked out. They wordlessly look at each other and decide to conceal “the thing that would make certain [Minnie’s] . . . conviction.”
At first, Mrs. Peters tries to put the box in her handbag, but she finds it is too big. She considers taking the bird out of the box but finds herself incapable of touching it. Then Mrs. Hale steps in and puts the box into her pocket, just as the men return.