Why would Marguerite's Easter dress have to be a white woman's throwaway?

In the book, Marguerite's Easter dress was made from a white woman's "faded purple throwaway." Initially, Marguerite remembers being excited about the dress as she watched her mother put careful stitches on it. However, in the light of the sun, Marguerite found herself greatly disappointed in the dress, as it presented her in an unattractive light.

Because of her family's poverty, however, this was the only way Marguerite could have something semi-decent to wear to...

In the book, Marguerite's Easter dress was made from a white woman's "faded purple throwaway." Initially, Marguerite remembers being excited about the dress as she watched her mother put careful stitches on it. However, in the light of the sun, Marguerite found herself greatly disappointed in the dress, as it presented her in an unattractive light.

Because of her family's poverty, however, this was the only way Marguerite could have something semi-decent to wear to the Easter celebration in church. Although she was resigned to her fate on that particular Easter morning, Marguerite remembers feeling greatly ashamed that the faded color of the dress shouted out her poverty for all to see.

To comfort herself, Marguerite remembers fantasizing that her hair was really long and blond, her eyes blue, and her skin white. She imagines that it was a "cruel magician" who turned her into a "too big...girl, with kinky black hair, broad feet, and a space between her teeth that would hold a pencil."