The quilts are either an object that has real value, (both practical and sentimental), or they are a symbol of a past the Wangero has overcome. Maggie will use the quilt for warmth, not just physical warmth but also she is literally wrapping her family heritage around her. This is an honorable way of cherishing a hard fought heritage. Wangero views her past as an obstacle she has overcome. She wants the quilt almost as a prize or trophy, a symbol of her development past this shameful, low start. This treats her heritage as an idea. It objectifies her family and dehumanizes them.
It is also worth mentioning that the decision is with the momma as to whether Dee is not denied again (Maggie mentions the whole world always says "yes" to Dee) or if Maggie actually wins for once. The quilts are hanging in the balance. They have been promised to Maggie as part of her dowry for her upcoming marriage. Dee swoops in and just expects to be catered to once again. The climax lies in the fact that Maggie slams the door after saying Dee can have them (something Maggie never does) and the slamming wakes Momma enough to say, "Enough is enough. Maggie gets the quilts. You can have these other quilts. Don't like it? Tough". With that, Dee and her fancy boyfriend leave accusing Maggie and Momma of being ignorant of their heritage. It is actually Dee, who only plays the part of the heritage guru and who doesn't know how to quilt, cook, sew, or churn butter.
I think that the quilts illustrate the difference in the two sister's personalities. For Dee, the quilts are material goods. Before her quest to rediscover her roots, Dee had nothing but distaste for her family's old and worn possessions. But, now that they are in fashion, and are now worth money, Dee wants to take them and display them. Dee professes to have changed, but she is still materialistic and overbearing.
Maggie, as Dee points out, wants to use them. It ties in with the title, as the quilts would have an everyday use in Maggie's possession. Maggie connects the quilts with their heritage. The quilts are made of scraps of cloth from their family, and this is precious to Maggie.
It is fitting that the quilts are used to give justice to the sister who usually takes second. The quilts will be used every day in Maggie's house, and in this way, the family memories are kept alive. Maggie and her mother have pride in their family and home, whereas Dee has always hated it.