Frankly, my dear. . .

This scene from the film Gone With the Wind shows Gerald O'Hara (Thomas Mitchell) looking through his late wife, Ellen's, sewing box, holding up her earbobs, right after we first hear him speak of her as still being alive. Scarlett has just figured out that her father has become mentally unstable. He has her gold thimble on his left-hand pinkie. This scene in the book is different, with no reference to Ellen's thimble. There are only four thimble references in the novel, quoted below.
A lot of the sociological writings I've read regarding references to thimbles in art and film and literature take a feminist stance as to what thimble-wearing in represents: Patriarchy feels Woman is weak and must be protected by its own contrived devices. Or: Patriarchy is dulling the sensation of Woman's finger in the guise of protecting her but really just controlling her sexuality (Huh?). Or: Woman is either (A) oppressed and recoiling from her life into a capitalist-male-created thimble-shell, or (B) empowered and seizing control of her life by "donning her armor" and seizing economic opportunities in the workforce. Of course, an artist can use any symbol for any reason, including any of the foregoing. I don't think that Margaret Mitchell or Victor Fleming or David O. Selznick had such things in mind.
I do think Ellen O'Hara's gold thimble sort of posthumously personifies her, in both the book and the film. Practical and dutiful, yet elegant and uncommon. But then again, sometimes a thimble is just a thimble.Chapter 3, p. 41. [Scarlett has just returned to Tara from Atlanta, to find that her mother has died.]:

Scarlett had never seen her mother's back touch the back of any chair on which she sat. Nor had she ever seen her sit down without a bit of needlework in her hands, except at mealtime, while attending the sick or while working at the bookkeeping of the plantation. It was delicate embroidery if company were present, but at other times her hands were occupied with Gerald's ruffled shirts, the girls' dresses or garments for the slaves. Scarlett could not imagine her mother's hands without her gold thimble or her rustling figure unaccompanied by the small negro girl whose sole function in life was to remove basting threads and carry the rosewood sewing box from room to room, as Ellen moved about the house superintending the cooking, the cleaning and the wholesale clothes-making for the plantation.

Chapter 26, p. 440. [A Union soldier has just arrived at Tara and has found Ellen O'Hara's sewing box.]:

"Who's there?" cried a nasal voice and she stopped on the middle of the stairs, the blood thudding in her ears so loudly she could hardly hear him. "Halt or I'll shoot!" came the voice.
He stood in the door of the dining room, crouched tensely, his pistol in one hand and, in the other, the small rosewood sewing box fitted with gold thimble, gold-handled scissors and tiny gold-topped acorn of emery. Scarlett's legs felt cold to the knees but rage scorched her face. Ellen's sewing box in his hands. She wanted to cry: "Put it down! Put it down, you dirty--" but words would not come. She could only stare over the banisters at him and watch his face change from harsh tenseness to a half-contemptuous, half-ingratiating smile.

Chapter 26, p. 443. [Scarlett has killed the Union soldier; Scarlett and Melanie are looking through the dead soldier's belongings.]:

The trouser pockets yielded nothing except a candle end, a jackknife, a plug of tobacco and a bit of twine. Melanie removed from the knapsack a small package of coffee which she sniffed as if it were the sweetest of perfumes, hardtack and, her face changing, a miniature of a little girl in a gold frame set with seed pearls, a garnet brooch, two broad gold bracelets with tiny dangling gold chains, a gold thimble, a small silver baby's cup, gold embroidery scissors, a diamond solitaire ring and a pair of earrings with pendant pear-shaped diamonds, which even their unpracticed eyes could tell were well over a carat each.
"A thief!" whispered Melanie, recoiling from the still body. "Scarlett, he must have stolen all of this!"
"Of course," said Scarlett. "And he came here hoping to steal more from us."

Chapter 27, p. 467. [Union soldiers are at Tara, scavenging for food and items of value.]:

"Nothin' but cotton in the cabins. We set fire to it."
For a brief instant Scarlett saw the long hot days in the cotton field, felt again the terrible ache in her back, the raw bruised flesh of her shoulders. All for nothing. The cotton was gone.
"You ain't got much, for a fac', have you, lady?"
"Your army has been here before," she said coolly.
"That's a fac'. We were in this neighborhood in September," said one of the men, turning something in his hand.
"I'd forgot."
Scarlett saw it was Ellen's gold thimble that he held. How often she had seen it gleaming in and out of Ellen's fancy work. The sight of it brought back too many hurting memories of the slender hand which had worn it. There it lay in this stranger's calloused dirty palm and soon it would find its way North and onto the finger of some Yankee woman who would be proud to wear stolen things. Ellen's thimble!

I appreciate Scarlett's sentimentality about her mother's thimble, but she might want to consider her own pride in wearing things acquired from the proceeds of stolen labor.