Are there any American foods that if not prepared right, by an expert, can make one sick? (Details Inside)

In America, we generally cook the shit out of food.
The only food that I can think of that might fit your description would be Thanksgiving turkey, which some people cook at alarmingly low temperatures.

Chicken not fried properly.

I don’t think any food available (in the west at least) that require an expert level of skill to prepare safely. Everyone knows about undercooked meats, but here are some other dummy food moves that can have bad outcomes.

Fiddleheads, undercooked, can cause gastric distress.
Green potatoes can kill you, and so can the leaves if you eat a bunch of them for some reason.
A person once ate leftover spaghetti and meat sauce that had been left out for a few days, and actually died from it.
Ingesting a massive dose of sodium, say from a mixed up supplement or a viral pickle brine challenge, can cause permanent brain damage.

Poke Sallet is said to kill you unless cooked properly. It was NEVER served in my family so I don’t know if it’s true or not. My neighbor planted some in his yard & it’s taking over the neighborhood & it’s extremely invasive. I understand that birds love it & that’s how it spreads so rapidly. If I need to do any work on some that made it into my yard, I always wear gloves to make sure I don’t get the juice on my hands.