No. Grapeshot was manufactured as such. Not just random junk. It was called that because people thought the smaller balls inside looked like grapes. It basically was like a giant shotgun shell that fit the cannon.
Correct, loaded into a burlap bag to keep it all together during loading.
Scattershot
An improvised form of grapeshot made of whatever came to hand - nails, glass shards, rocks - anything hard enough to cause some damage. This only worked at close range, and badly at that, as the ballistics of these improvised projectiles was very random.
I'm not talking about civil war era rifled artillery like the Union had in larger numbers, because that can only be loaded with shells that were made to work with it.
I'm talking about smooth bore, muzzle loading cannons.