Ruth's Engagement Ring

"True love follows this ring wherever it goes, my son...Take it, and I'll know, even if I never see you again, I'll know you'll find love. I'll know you'll be happy."

- Ruth to her son

The green peridot ring is an item Mary Margaret Blanchard 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
Charming, a shepherd boy on a farm, assumes the role of prince due to his twin brother having been adopted by King George years ago and dying 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. Charming must tackle the mission now that he has taken his brother's place. Upon the successful slaying of the dragon, King Midas, who was both impressed by Charming 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 Shepherd")

The ring is then placed in a jewelry box for safekeeping and taken along in Princess Abigail's carriage when Charming and Abigail set out for their engagement party. A fallen tree blocks their way, which was actually a trap set up by a vagabond Snow White. While Charming 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 Charming even after he catches up with her, and later sells the ring to the trolls who reside on the Troll Bridge. Charming 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 Charming by tricking and running away from him, but instead she faces danger when the Evil Queen's Black Knight captures her. Prince Charming 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 Charming's belongings, they find the wanted poster of Snow, and conclude they would receive more in rewards if they turned her in. Charming tries to distract them while Snow prepares to run but the trolls grab Charming, so Snow resorts to using the Fairy Dust she has been carrying around, in which the dust transforms the powerful enemies into harmless insects. Having gotten Charming's 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. ("Snow Falls")

The ring becomes one of Snow White's possessions that stayed with her until the very end when the Dark Curse was enacted. Thus, Mary Margaret still has the ring in Storybrooke. ("Pilot")

When Charming breaks free of the Evil Queen's castle with the help of the Huntsman he comes upon Rumplestiltskin. Rumplestiltskin takes the ring and magically enchants it so the closer he is to Snow's presence, the brighter the ring's gem glows. He won't give it back to him without a price, though. After Charming agrees to a deal of hiding Rumplestiltskin's true love potion in a beast and succeeds, he sets off to find Snow using the ring. It guides him to her, and with true love's kiss, he awakens her from the sleeping curse. ("A Land Without Magic")