https://www.cocktailsafe.org/" onclick="window.open(this.href);return false;" rel="nofollowCocktailSafe.org is a website dedicated to safety in cocktail ingredients and techniques. This is the index of all the safety pages, many of which are still under construction.
Two that stand out to me are Tonka beans and Cinchona bark. Tonka beans are illegal in the US to put in a drink (FDA ban list) but are easily available other places. The use of Cinchona bark is limited. In small quantities they are fine. In larger quantities their toxicity adds up. Commercially it's not an issue, but be careful making stuff at home with them.
https://www.cocktailsafe.org/coumadin-coumarin.html" onclick="window.open(this.href);return false;" rel="nofollow (Tonka beans)
https://www.cocktailsafe.org/quinine-to ... -bark.html" onclick="window.open(this.href);return false;" rel="nofollow (Cinchona bark)