Okay, it's time for me to have a controversial post, so I'm going to write one about Ethan Frome and the REAL meaning of that red pickle dish.
I may be the only person in the country who sees Mattie as being the villain of the book. She is like her father - charming, stupid, and worthless, with a habit of taking other people's things and making them disappear. In Zeena's moment of truth, she tells Mattie this - that she was warned against taking her in, because Mattie was just like her father, but she did it anyway out of the kindness of her heart; and now she was paying for it.
What would have happened if Mattie had decided to marry Denis Eady? She would have expected, and gotten, parties - presents - a pretty wedding dress, paid for by Denis's family - a new home with nice things, ditto - all the things a woman could hope to get when she married and established her household. Mattie had only to put out her hand and all this was hers. The pickle dish, empty as it was, and designed to hold sourness, had to represent all those things to Zeena. It was a gift from a relative, upon her marriage, and it was beautiful to her. She loved her pickle dish, and she knew how fragile it was, so she kept it in a safe place. As soon as her back was turned, Mattie took that pickle dish and broke it. Then she took Zeena's husband and broke him. He was a spineless wretch who let all that happen. At the end of the book we find out what Mattie's sweet nature is worth: when she no longer gets attention for being pretty, and can't dance, she's the harsh and spiteful one.
Now that's the real story of that pickle dish.