The first assumption that the males make in the play Trifles is that women have absolutely no worries or concerns to care for in life with the exception of tending to their homes and families.
We find evidence in the beginning of the play, when the country attorney and the sheriff scoff at the state of the house where Minnie Wright was found in a state of shock after having snapped and murdered her husband. The reader will find out later that Minnie was subjected to a tragic pattern of domestic abuse, and that her husband's murder was not planned. However, this is a big case either way, and still all that the men can do is criticize what they feel are Minnie's lack of domestic skills.
COUNTY ATTORNEY: Here's a nice mess.
MRS PETERS: (to the other woman) Oh, her fruit; it did freeze, (to the LAWYER) She worried about that when it turned so cold. She said the fire'd go out and her jars would break.
SHERIFF: Well, can you beat the women! Held for murder and worryin' about her preserves.
The silly, gender-digging dialogue goes all throughout the play. The county attorney, Mr. Hale, and the sheriff are equally guilty of promoting their thoughts of gender superiority.
COUNTY ATTORNEY: (with the gallantry of a young politician) And yet, for all their worries, what would we do without the ladies? [...] Dirty towels! (kicks his foot against the pans under the sink) Not much of a housekeeper, would you say, ladies?
MRS HALE: (stiffly) There's a great deal of work to be done on a farm.
Clearly, there is a line of respect and deference that the women do not dare crossing in challenging the men directly about their thoughts. However, Mrs. Hale and Mrs. Peters do their part subtlety. They try, as we just saw above, to counteract the words of the males. They also try their best to come in defense of Minnie. Mrs. Hale even tells of how Minnie had changed ever since her wedding; that the home became a sad and cold place where she never wanted to go and visit. .
Therefore, while the man continue their attacks against the "joys" of womanhood, the women focus on finding the cues as to what could be there that can help Minnie at least get evidence that she has snapped, and not that she is a cold-blooded killer.
Eventually the audience will find out that the so-called "trifles" that the men called on, and the women were looking into around the house, were much more than that. The audience finds out that the crazy stitching pattern, the frozen compote, and the house where Minnie kept her canary were not merely disparate objects around the house. They were all symptoms or consequences of the abuse that Minnie was enduring. Therefore, while the men continued to overlook the obvious, the women were sure to hide anything that would be negative for Minnie's defense.