If you're only running on shrooms & berries, it'll be quite hard to gather lox meat imho. Don't forget that you'll need ingredients to brew potions as well, they're not as important as food but they're an emergency ticket to avoid death sometimes.
When you find seeds plant them, then plant the vegetables, repeat a couple of times while exploring elsewhere and before you know it you got a couple of stacks of carrots and turnips. Don't forget to place stakewalls (preferably) around your fields.
New foods should arrived with the H&H update, so things should change a bit.