Is it possible to eat a toxic amount of culinary herbs/spices?

Actually a lot of spices contain unsafe levels of heavy metals, so you definitely could hurt yourself with them

You can easily kill yourself with a water overdose (and it's actually fairly common),so yes.

Nutmeg was already mentioned - high doses can easily kill someone, sadly even without hallucinations simply by killing off ones liver and dying an agonizing death a few days later. The same goes for cinnamon, but with a much lower dose.

There are a few more, but I don't want to give people too many ideas.

To make it short: Yes, possible,but it's mostly a very slow death over multiple days that fucks you up really bad and is a horrible way to go.

"The poison is the dose" is a saying for a reason.

Nutmeg is poisonous in high doses and can lead to hallucinations, seizures, and other complications.

The "Anarchist's Cookbook" covered this 😂
How much are we talking? Are there any documented suicides by nutmeg?
- 2 to 3 teaspoons is lethal. 1.5 to 2.5 will get you high though. I don't recommend it as you can see there is an overlap.
  
  Edit: Toxic. Not lethal
- IIRC when I took it recreationally itwas many many grams to get to the hallucinations part. It was hard to stomach. Unless the safety profile is pretty narrow I'd say it would be difficult to complete suicide with nutmeg.
- It's funny because I am cooking with nutmeg, and was saying that. A quick search tells me that you can have hallucination from 15g of nutmeg.
  
  However, with the strong taste, sounds like a good netty bad poison

Everything is toxic if you eat too much of it

Even water!
- Yep
... except cannabis, presuming you don't have a genetic disposition to schizophrenia. Nearly no one has ever died of a marijuana overdose. Compare that to alcohol (or, indeed, water). In fact, the only reason I say "nearly" is just in case; its safety has been known for a long time.

This is in fact one of the core reasons why I finally stopped being a straightedge and accepted taking it. (Though smoking is still a no-no and the worst way to experience anything, basically.)
- Toxic =/= deadly. You can absolutely consume enough cannabis to trigger a toxic response. It won’t kill you, but you may wish it did. Just because it’s not “deadly” doesn’t mean it’s good for you in any dose.
- Nearly no one has ever died of a marijuana overdose.
  
  That's just because the amount needed to OD is extremely large. You're more likely to die from other reasons consuming enough marijuana to OD from it.

https://en.wikipedia.org/wiki/List_of_herbs_with_known_adverse_effects

The list itself says it is incomplete and I immediately thought of a couple items not listed that have known toxicity issues:

https://en.wikipedia.org/wiki/Perilla_frutescens#Traditional_medicine,_phytochemicals,_and_toxicity

https://en.wikipedia.org/wiki/Ruta_graveolens#Toxicity

I mean, as humans, toxicity isn't a deterrent, it's a selling feature!

Yeah, the reason we like booze is because it's toxic and fucks up our brains.

All at once, absolutely, but it's going to take a LOT of most things.

Theoretically, anything is poisonous if you have enough of it. We even get oxygen poisoning by breathing air that is too rich in oxygen for too long.

Cinnamon can cause permanent damage in high doses.

Other than that and the others mentioned here, probably just old, rotting ones would be bad.

How high?
- It appears to be 0.1mg/kg of body weight too avoid coumarin overdose (which is much stronger in Cassia than ceylon cinnamon), which is toxic to the liver: https://ovidsp.dc2.ovid.com/ovid-new-a/ovidweb.cgi?T=JS&PAGE=fulltext&D=ovft&AN=01445481-201002000-00007&NEWS=N&CSC=Y&CHANNEL=PubMed

Licorice is not that common a spice any more, partially because it's toxic at pretty obtainable levels, though people who like the flavor still typically won't accidentally consume a dangerous amount.