In the beginning of the play Trifles the reader gets a description of the murder scene which also serves as the setting of the story.
The kitchen in the now abandoned farmhouse of John Wright, a gloomy kitchen, and left without having been put in order--unwashed pans under the sink, a loaf of bread outside the breadbox, a dish towel on the table--other signs of incomplete work.
This gives the reader a window into the mind of those who inhabited such an untidy and ugly place: Things were undone, incomplete, chaotic, and dingy. Certainly is not the place one would picture a happy homemaker living in harmony with her husband.
Other clues come up that help us understand the situation of Mrs. Wright. Mrs. Hale described her the following way.
She didn't even belong to the Ladies' Aid. I suppose she felt she couldn't do her part, and then you don't enjoy things when you feel shabby. She used to wear pretty clothes and be lively, when she was Minnie Foster, one of the town girls singing in the choir. But that--oh, that was thirty years ago.
These are clear indicators that there had been a major change in the personality of Mrs. Wright after she got married. Considering the state of her kitchen (a woman's domain), and the state of her own appearance, we can conclude that Mrs. Wright was a woman too depressed, or oppressed, to take the time to care about aesthetics.
Finally, the scene of the dead bird which had its neck broken leads us to realize that Mr. Wright must have been an abusive husband, that he killed the bird (Mrs. Wright's only companion), and that Mrs. Wright must have snapped and killed her husband.
Therefore, the setting is a mirror of the state of affairs in the Wright household: One that is depressive, abusive, and in complete chaos.