Mushrooms are “fruits”. The “plant” itself is the mycelium underground and the mushroom is the “fruity” part which is produced to spread the “seeds” (spores).

And fruits are broader than most people think. Many of the things you think as vegetables are fruits: pumpkins, zucchinis, tomatoes. But even outside fruits there is food you can harvest without harming the plant, like potatoes. And we haven’t even gotten into seeds and grains, like rice.

So you can definitely live without killing what you eat.