The description 'natural' is debatable, since things can be bred to increase their potency.

Does ricin count as natural?

Note I didn't say "should be completely unscheduled". Schedule 1 is extremely strict to the point of making medical research virtually impossible. We've known there are major medical benefits to many substances on schedule 1 for decades now, yet the government definition still declares them the opposite, which at the very least is a lie.

Ricin is not a plant. It is a chemical produced by the Castor Bean plant which is widely grown in gardens.