OK. how about this. There are lists all over the internet. and BYC. They disagree. Frequently.
The best thing you can do for your birds is to offer them a commercially complete feed as their sole ration. That you are asking the question at all is evidence you lack the training and experience to evaluate the nutritional needs of poultry, and the value (or concerns) of your scraps. I appreciate that you want to do right by your birds - that's a worthy goal.
But there is NO answer. Certainly not a short one.
Lets talk Corn. Most chicken feeds, and most chicken "scratch", contain corn. You absolutely *can* feed your chickens corn. Corn has insufficient protein to meet a chickens needs, and has to be supplimented with other ingredients to provide a complete diet. Even if you were to use certain high protein corn by products, the amino acid profile of corn won't meet the bird's needs, even if you can get to the 16% protein or so generally considered minimally acceptable here in the US. Your birds would starve to death on it, though you met the target fat, fiber, and protein numbers. Adding corn to the diet reduces the overall value of their daily nutrition.
How about Oats? Again, very popular ingredient in chicken feed. But Oats are high in beta-glucans, which slow digestion, makes some vitamins harder to absorb, and contribute to sticky fecals - which can cause its own problems. With the right enzymes, it can be used in excess of 50% of the diet, assuming you can hit the other targets. Without? Shouldn't exceed 10-20% (sources vary).
Soy? Hugely popular. One of the best plant sources for methionine, a critical limiting amino acid, and has a good AA profile overall. Its also high protein. Has to be heat treated (all legumes do) to neutralize some anti-nutritional factors. Peas and beans? The same. Though not all peas are the same...
BOSS (Black oil sunflower seed) - great protein, high in a few amino acids, useful for addressing ares where grains are deficient. Without the shell, fiber is very reasonable. Also, a monsterous source of fat. Contributes to fatty liver disease and sudden poultry death from internal hemorrhaging.
Calcium, critical to growth, numerous biuological functions, and of course egg laying nice hard shells. Too much? Calcium toxicity causes gout, tumors, intestinal and renal issues of all sorts, blocks nutrient absorbtion - particularly in cockerels, but can occur in hens as well.
Essentially, there is no ingredient a chicken can eat that isn't dangerous to them in excess, or if improperly treated - but if you provide them a commercially complete diet as their primary (and sufficient) feed source, they won't be starving enough to eat something they "shouldn't" to the point that it causes them distress or illness.
People will tell you potato skins will kill them. Sure. So will water. "The Dosage is the Poison." Green (underripe) potato just under the skin is actually far more concerning, but a healthy well fed bird might pick at it, then quickly find something else to eat. No harm, no foul.
Tomatoes? Part of the nightshade family. So what??? Chickens eat tomatoes all the time. Even, gasp, the leaves! But not to excess - they won't deliberately poison themselves, given better quality food to eat.
Now, there are some plants which contain high levels of phytotoxins (light reactive toxins) which are hazardous to chickens (and you, and almost every other thing) - even if you give them to your birds, if they have the choice of something better, after exploring it with their beaks, they will raise their noses and walk away.
I don't mean to demean, but I hope that helps illustrate that the question you are asking is not the question you want answered - that question is highly fact specific, and begins with "I was planning to offer my chickens "X", any concerns???"