You must go to specific locations to meet people who don't let the law get in the way of their dealings. This type of store is called a fence, and here is where you can find all of them in the game.

Red Dead Redemption 2 Kits and Tools Some items in RDR2 will provide ... normal Herbivore animal to its location Crafted/Found/Purchased from General Stores, Fences, Tackles Reutlinger Pocket ...