While traveling through Mirkwood, Thorin's Company come across the Enchanted Stream:
“"Come here Fili, and see if you can see the boat Mr. Baggins is talking about."
Fili thought he could; so when he had stared a long while to get an idea of the direction, the others brought him a rope. They had several with them, and on the end of the longest they fastened one of the large iron hooks they had used for catching their packs to the straps about their shoulders. Fili took this in his hand, balanced it for a moment, and then flung it across the stream.”
It's very unlike Tolkien to describe something that's not the landscape so specifically (The Hobbit is funny like that). Might anybody have an idea what sort of pack he might be referring to or trying to suggest here?, or know of any historic backpacks that attach to shoulder straps via metal hooks?
It's also a bit confusing as the Company's pony-baggage was lost in Goblin-town; so did they have backpacks that survived the trip through the Mountains? I expect that is more likely than thinking that these packs come from Beorn (to hold the food he gave them).
For what it's worth, here is a sketch the Professor made of a line of marching dwarves.