History of drug use is very long in human civilization. Hence it is not surprise that you could get a drug from very common substances and plants around you. And no, we are not talking about using the plants and other natural psychedelics per se, like marijuana or shrooms.
There have been many scientific studies about drugs and psychedelic substance levels in plants and the reasons why they are there, awareness of animals about these substances and many more. And of course the history of psychedelic and painkiller substances in human evolution:
…concerning human species, using psychoactive substances has a very long history. There is evidence for use of betel nut in Timor, which dates some 13,000 years back, which is still in the use today, just to name one example. Also, opium, mushrooms, marijuana, nicotine, and many other plants containing psychoactive substances have been found on many prehistoric archaeological sites throughout the world. There is also some evidence from 30- to 48,000-year-old specimens from El Sidrón cave in Spain that Neanderthals have also been using some painkillers and plants with psychoactive substances.
But in today’s time we of course have a huge range of natural and synthetic drugs of course since humans apparently never stopped experimenting with drugs (and it seems they never will). Most of the drugs are not legal in majority of countries. That, however, does not imply for the ingredients substituted in them. With a little knowledge of chemistry, anyone can make some of the illegal drugs using legal ingredients.
As we have noted before, you might get surprised that some of the common plants you can find around can be used for making heavy drugs, such as mimosa or Morning glory. If you are interested which drugs you can get with these plants, and also which legal ingredients you can combine to get drugs, check out the article about the 7 Easiest Illegal Drugs to Make at Home by Using Legal Ingredients.