There are many merchants in Sekiro: Shadows Die Twice. These NPCs will buy from you useless items or sell various consumables like Pellets or Antidote Powder. Below you can check where you can find Crow's Bed Memorial Mob and what you can buy from him.
Where can I find Crow's Bed Memorial Mob?
The first merchant is in Ashina Outskirts - Outskirts Wall - Path to the Gate. You can find him right after you beat the first boss (behind the second gate starting from the checkpoint) - he is on top of a lone hill, inside a black tent.
To get there, you have to go around the mountain and climb in the place near another fortified gate. Use the grappling hook twice to reach the top.
What can you buy from Crow's Bed Memorial Mob?
The first merchant doesn't offer much items. Treat him more like a place where you can sell useless loot. Robert Firecrackers are the most interesting item in his offer - they unlock Shinobi Firecracker upgrade for your prosthetic.
Robert's Firecracker - an important crafting item for a new prosthetic tool (Shinobi Firecracker)