Your search for "Boros Signet 107" revealed the following:
Boros Signet (Foil) (RAV) from Ravnica: City of Guilds, available at 401 Games Canada. Rarity: Common Finish: Foil Artist: Greg Hildebrandt Card Text:1, T: Add RW to your mana pool.
Boros Signet (HOP) from Planechase, available at 401 Games Canada. Rarity: Common Finish: Normal Artist: Greg Hildebrandt Card Text:1, T: Add RW to your mana pool.
Boros Signet (C17) from Commander 2017, available at 401 Games Canada. Rarity: Uncommon Finish: Normal Artist: Mike Sass Card Text:1, T: Add RW to your mana pool.
Boros Signet - Dan Frazier is Back Secret Lair (Etched) (SLD) from Secret Lair Drop, available at 401 Games Canada. Rarity: Rare Finish: Foil Artist: Dan Frazier Card Text: Dan Frazier is Back: The Enemy Signets1, T: Add RW.