Symbolism in The Yellow Wallpaper
the pattern of the wallpaper- The pattern is meant to represent the fact that she sees herself as this women who is trapped in the house. At first she doesn't realize that she is trapped, which is in the beginning when she doesn't recognize the pattern. She doesn't realize how trapped she is in the house until she has to spend so much time there, that she can't help to realize how she is trapped, without any stimulation. The fact that she is in a cage, shows how the house is like a cage to her. She touches this when she realizes because it is almost as if she is caged in on the opposite side of the women in the wallpaper, and neither know how to get out.
The color yellow-I'm less sure about this one than the pattern, but I'm pretty sure the yellow represents the sickness she feels, and how the she is losing the purity of her ignorance. She is beginning to see how trapped she is, so she is losing that purity, of being a good housewife.

Symbolism in The White Heron
The color white-in the same way that yellow represented the loss of purity, I think that the white in the story represented the purity of her heart. Not meaning she was ignorant to her oppression, but that she was so pure and good in her heart that she couldn't tell the hunter where the white heron was.