In the book Chains by Laurie Halse Anderson, why is the silver tea set important to Lady Seymour?

The silver tea set is likely important to Lady Seymour for a couple of reasons.  First, it is silver, so it is valuable.  She is a member of the upper class, and a silver tea set allows her to host guests in style.  

That is not likely the main reason for its value to Lady Seymour though.  She is wealthy, so she can afford another one.  When her house burns down, Lady Seymour and Isabel try to rescue a trunk full of stuff from the house.  The silver tea set is in the trunk, and Lady Seymour frantically cries out to Isabel that it contains her "valuables."  Unfortunately, the trunk is simply too heavy to be lifted out of the house by the two women.  Lady Seymour is forced to open the trunk and choose which items to take.  In the trunk is the tea set, a small portrait of her late husband, some small wooden boxes, and letters.  Lady Seymour chooses to save the letters, the boxes, and the portrait.  She does not choose to save the tea set.  

I believe the tea set is valuable to Lady Seymour for sentimental reasons.  It's in the trunk that contains a portrait of her husband and likely letters that he wrote to her.  I believe the tea set reminds Lady Seymour of her husband, and that is why it is valuable to her.