Woetorix
The crates are found on the floor in some of the shops. Not all shops but if you look for them they look like a plain wooden crate. If I remember correctly, when you approach then, they say "Inventory" and when you use them, you can put items in there just like you can in your traveling inventory! I am using them to store the items I need to produce items in the shops...instead of carrying everything around throughout the countryside and slowing down movement speed on the world map. As an example: Tools, bolts of cloth, spinning wheel, furs, hides, leather, keg of tannin for the tailor/tannery!
Reminder: Don't forget to purchase those extra pack horses if your are carrying inventory...it speeds up your movement on the world map...up to a maximum of 3 horses, from what I've read.