During Chapter 2 of the main story, you'll find Phineas T. Ramsbottom sitting on a bench outside Flatneck Station. Upon speaking to him, you'll learn about his love for Cigarette Cards and then task you with tracking down all 144 in the game world for him. For each set that you complete, he'll provide a reward for you so focus on completing sets while on the search.
This is a rather long Stranger Mission that will most likely take your whole playthrough to complete, these Cards are hidden everywhere. There is an alternative, you can purchase or loot Premium Cigarette Packs that will yield a card (which can be one you already own) once opened. The Interactive Map will point out where to find each individual Card and you'll find the rewards below.
|First||Vintage Civil War Handcuffs|
|Amazing Inventions||Volatile Dyanamite, $100|
|Artists, Writers, & Poets||Ginseng Elixir, $100|
|Famous Gunslingers||Special Snake Oil, $50|
|Fauna of America||Perfect Rabbit Pelt, $50|
|Flora of America||Special Miracle Tonic, $50|
|Gems of Beauty||Platinum Chain Necklace, $100|
|Horses||Special Horse Medicine, $50|
|Marvels of Travel||Aged Pirate Rum, $50|
|Prominent Americans||Eagle Feather x3, $50|
|Stars of the Stage||Small Jewelry Bag, $50|
|Vistas of America||Gold Nugget, $100|
|World Champions||Valerian Root, $50|