You're affirming the consequent. We don't have receptors for plants found in the wild (cannibis, nicotine, etc). Rather, compounds formed by those plants match

You're affirming the consequent. We don't have receptors for plants found in the wild (cannibis, nicotine, etc). Rather, compounds formed by those plants match up with receptors we already have. There's an entire endocannabinoid system, and it's not because pot is natural. Nicotine broadly matches up with acetylcholine and nicotonic acetylcholine receptors. It's far more likely that plants evolved and selected for compounds which have beneficial/detrimental effects on possible consumers, like nicotine as a pesticide, than it is that we have receptors for plants found in the wild on the off chance that we may have consumed them or that they would have been so prevalent in the past that receptors for them would have been selected for.