The idea that Mrs. Wright was going to knot her quilt rather than sew it comes up over and over in the play, pointing to its importance.

When a person knots a quilt, he or she uses fewer stitches, sewing together all three layers at once and then securing the stitching with a knot at the end.

The men repeatedly make fun of the women, Mrs. Hale and Mrs. Peters, for wondering if Mrs. Wright was going to sew or knot her quilt. They feel that while they are doing important investigative work, the women are obsessed with meaningless "trifles," showing their weak-mindedness:

SHERIFF: They wonder if she was going to quilt it or just knot it!

[The men laugh, the women look abashed.]

The women, however, by focusing on all the details the men overlook, are actually "piecing together" (like a quilt) what really happened in a careful and methodical way. They can reconstruct the scene that led Mrs. Wright to murder her husband.

Mrs. Wright was knotting her quilt when her husband entered the kitchen. The canary must have been singing, and this must have thrown Mr. Wright into a fit of rage. He reacted by breaking open the door to the canary's cage, pulling the canary out, and wringing its neck. This upset Mrs. Wright, whose sewing went awry. Something snapped in her, leading her to knot a rope around her husband's neck while he was asleep and strangle him. Because the women have reconstructed the details, they know that Minnie was experienced at making knots and that perhaps the fact she was knotting as her husband killed the canary gave her the idea for how to murder him in a way that mirrored how he killed the poor bird.

Nevertheless, the men completely miss this, as they miss the significance of the missing canary, as well as the body of the canary that is carefully wrapped and put into a drawer. Instead, they condescend to the women:

COUNTY ATTORNEY: (as one turning from serious things to little pleasantries) Well ladies, have you decided whether she was going to quilt it or knot it?

MRS PETERS: We think she was going to—knot it.

COUNTY ATTORNEY: Well, that's interesting, I'm sure. (seeing the birdcage) Has the bird flown?

MRS HALE: (putting more quilt pieces over the box) We think the—cat got it.

The count attorney has shown his cluelessness and is easily deceived.

The play ends with the image of a knot. The men continue to make fun of the women, and the women continue to keep to themselves what they know:

COUNTY ATTORNEY: (facetiously) Well, Henry, at least we found out that she was not going to quilt it. She was going to—what is it you call it, ladies?

MRS HALE: (her hand against her pocket [with the dead canary]) We call it—knot it, Mr Henderson.

In the process of quilting, three layers of material are used. After these are stitched, there are two ways to finish off the making of a quilt: knotting or quilting. Quilting is a method that imitates the process used throughout the making of the quilt. Knotting is the quicker method because it involves limited stitching. To "knot," one simply sews down through the three layers used in making the quilt, returning the needle near the entry stitch, then tying a knot with the two ends. Interestingly, "knot it" is also an embroidery term that means to end a stitch.

Judging from the erratic stitching on Mrs. Wright's quilt that is discovered and restitched by Mrs. Hale, it is possible that Mrs. Wright may have been in the act of quilting when Mr. Wright killed her canary.

MRS. HALE. . . . Wright wouldn't like the bird—a thing that sang. She used to sing. He killed that, too.

Perhaps, then, in the desperate loneliness and rage that filled her after her husband destroyed the only thing of joy that she possessed by twisting the canary's neck and killing it, she decided to wrap a rope around Mr. Wright's neck and "knot it" in retaliation.

In Trifles, John Wright is dead and the circumstances of his death are very suspicious, especially as he "died of a rope round his neck," says his wife without any display of emotion. Mr. Hale had approached the farm house wanting to talk to John about the possibility of installing a telephone line and it is he who notifies the police, as Mrs. Wright sits rocking in her chair, her apparent lack of any real awareness making Mr. Hale feel uncomfortable. 

After Mrs. Wright has been taken to the courthouse, the men who come to the house to investigate the circumstances of the assumed murder are immediately judgmental and comment on Mrs. Wright's obvious lack of "the homemaking instinct." The women jump to her defense and remind the men how difficult it is to be a farmer's wife and also how unfriendly John Wright was.

As the women gather some things to take to Mrs. Wright, they notice the quilt that she has been "piecing" and Mrs. Hale wonders whether her intentions were  "to quilt it or just knot it." The men overhear this conversation and mock the women's concerns because, while they investigate a murder, the women worry over "trifles." The county attorney even repeats the question and the women decide that she was most likely going to knot it. It is also significant that the presumption that Mrs. Wright would have intended to "knot" it is the last line of the play. 

A quilt is a blanket and so symbolizes warmth, something that Mrs. Wright never got from her husband. In this era, quilting would also have been a social activity where women would meet and help each other to quilt whilst exchanging gossip and advice. The act of knotting the quilt is a considerably easier task in blanket-making (although both methods achieve a completed quilt) and it is therefore an important reference in the play because it emphasizes the theme of loneliness and isolation as Mrs. Wright has no social circle and is much a victim as she is a potential killer. 

The final stage of quilting is to attach the top, batting, and backing together. This can be done in two ways. One way (quilting) is to sew elaborate patterns on it. The simpler but just as effective way (knotting) is to sew a thread through intervals and tie knots in it.

The symbolism of the knotting is the fact that Mrs. Wright killed her husband by tying (and knotting) a rope around her neck. simple, not elaborate, but just as effective.