Ruth's Engagement Ring

Mary Margaret 's green peridot ring is an item she is shown to have worn in Snow Falls. The ring is the only item of Mary Margaret's from her previous life as Snow White which she retains in Storybrooke.

History
The ring's backstory in Fairytale Land is revealed in The Shepherd. James, the shepherd boy on a farm, assumes the role of prince due to his twin brother, having been adopted by King George years ago, who suddenly died at the hands of Behemoth during a sparring match. The mission his twin brother was supposed to have undertaken was to defeat a great dragon. James had to be responsible for completing the mission now that he is in his brother's place. Upon the successful slaying of the dragon, King Midas, who was both impressed by James and wished to join his kingdom with King George's, gives his daughter, Princess Abigail to him in marriage. Now he has no choice but to assume the role of prince and cannot go back to his mother, Ruth, so she gives him her engagement ring as a parting marriage gift.

The ring is then placed in a jewelry box for safekeeping in Snow Falls and taken along in Princess Abigail's Carriage when James and Abigail set out for their engagement party. A fallen tree stands in the way blocking their path, which was actually a trap set up by the vagabond, Snow White. While James and his men were busy trying to figure out how to move the obstruction, Snow reached into the carriage, grabbed the jewelry box and took off on horseback to flee. She outruns James even after he catches up with her, and later sells the ring to the trolls who reside on the Troll Bridge. James manages to ensnare Snow in a net, and forces her to help him get back his ring or else he will turn her over to the Evil Queen, who wants her dead for murder and treason. During the ordeal, Snow once again tries to outsmart James by tricking and running away from him, but instead she faces danger when the Evil Queen's Black Knight captures her. Prince James saves her by killing all of the black knights. They continue onto the Troll Bridge, where they meet the Troll Group. The trolls are very unhappy that Snow is asking for the jewels in the box back, but also that she brought a stranger with her. After sifting through James' belongings, they find the wanted poster of Snow, and conclude they would receive more in rewards if they turned her in. James tries to distract them while Snow prepares to run. But, the trolls grab ahold of James, so Snow resorts to using the fairydust she has been carrying around, in which the dust transforms the powerful enemies into harmless insects. Having gotten James' jewels, including the ring back, they set out to part ways soon after. Snow tries on the ring jokingly, and says it isn't her style.

Of course, when Snow becomes James' bride-to-be in The Thing You Love The Most, the ring becomes one of her possessions that stayed with her until the very end when the Dark Curse was enacted. Thus, Mary Margaret still has the ring in Storybrooke.