While heroin does come from the poppy, and eating a poppy muffin will have negative affects on a drug test, according to PBS, heroin is made from the sap of the pod, not the seeds themselves. I don't think sitting down with a bag of poppy seeds and s spoon is going to do much.
While catnip may get cats feeling frisky, I've heard of people trying to smoke catnip thinking they'd get the same effect. They said it didn't work. However, it does make for a rather nice tea.
Some friends told me once that while they were in college, they had heard eating nutmeg could have a narcotic effect. So they sat down, ate a bunch and...nothing happened. That is, until the next day when their parents came to town and they - the students not the parents - were completely hung over. I'm not sure which is worse - experimenting on getting high the night before your parents come to town, or being all hung over without any of the "fun." While I make light of this, it's really not. It is possible to get high on nutmeg, but it's truly a stupid idea trying.
If you really want to get high, get the endorphins going. Exercise and get that heart pumping. Get all sweaty in the sauna and then jump under a cold shower (or snow if it's around). Or my favorite, eat some chili peppers!
Narct*, by the way, is very uncommon in library catalogs.
(Photo is from Wikipedia - it pretty much speaks for itself.)