The legalities around gathering wild plants and fungi aren't very complicated in Norway. The general rule is that you can pick whatever berries and nuts you want as long as they are wild. The same goes with fungi and herbs. Herbs can be uprooted, but protected species are of course not to be touched. There are two moderators of this freedom:
Nuts can only be gathered in quantities to be eaten on the spot without permission from the landowner.
In Troms and Finnmark counties cloudberries are only to be gathered in quantities to be eaten on the spot without permission from the landowner.
Unripe cloudberries are illegal to pick.
In practise, very few gather nuts today. I strongly doubt that anyone will object against you harvesting as much as you like of that resource.
Cockles, mussels and sea weeds are to my knowledge legal to gather, but I was unable to verify this.
Rocks, antlers, bone are illegal to gather. It is however commonly accepted that gathering small amounts of such worthless materials, without the permission of the landowner, is legal.
Next Monday: Hunting