Her obsession with finding a pattern reveals her imagination and creativity, which is stifled by her husband and by her being forced to spend so much time in the room.
She is depressed, not able to see her new baby, not permitted to have visitors, and shut in at all times. Since she is denied any opportunity for stimulation or creative outlet, she creates one. Her obsession with the wallpaper, and later the insanity it causes, show what kind of a mind she has. Her mind is one that needs to express itself creatively.
“any girl or boy who has not reached adulthood, for whom the street (in the broadest sense of the word, including unoccupied dwellings, wasteland, etc.) has become her or his habitual abode and/or sources of livelihood, and who is inadequately protected, supervised or directed by responsible adults”
