Apples
Nature's grenade.
Apples alone can be delicious foods; You can eat them raw, bake them, and even use them for cheap decorations. But if you included the seeds, you just increased your chance of dying by 1.34%.
Unlike Snow White, you don't need to find a poisonous apple and a naive prey. Apple seeds naturally contain the chemical, Cyanide, which isn't something recommended for daily intake.
Cyanide salt capsules have been used in history for many famous suicides, such as Adolf Hitler and his wife. But we aren't looking at capsules of death inside of fruit here.
"A risk in every bite"
In order to actually become poisoned by apple seeds, you need to do various things nobody would ever do. Simply eating all the seeds of a single apple won't kill you, and when I said "eat", I don't mean swallow with a gulp of water. I mean chewing the seeds violently, allowing the cyanide to come out.
You'll have to chew and swallow more than a small handful of apple seeds in order for the cyanide to take effect. Not exactly something people commonly do. (Since all the people who did, are dead for obvious reasons.)
Almonds
Not even Almonds are safe from our condemnation. Almonds can be extremely poisonous in certain cases. Naturally occurring bitter almonds are highly concentrated with Cyanide. In fact, the concentrated amount of Cyanide in unprocessed Almonds are so high, some countries make it illegal to sell almonds that aren't processed properly.
Does that mean that everybody that has ever eaten Almonds, will die? No. Bitter almonds can be rendered safe to eat by introducing some type of heat source towards the seed.
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But remember, if you end up eating a bitter almond, it doesn't mean you have a few hours to live. At the most extreme, you'll suffer vomiting, headaches, sickness, and shortness of sight. But that doesn't mean that you should keep chomping away at bitter Almonds like chipmunks on peanuts.
Cherries
We're not skipping a beat here, everybody's going down. Cherries are essentially "poisonous" in a manner of speaking. Like the above foods, the seeds are poisonous. As of now, it's pretty safe to simply not eat any seeds.
Amazingly enough, the pit of a cherry contains cyanide. As unsurprisingly said before, chewing the seeds will result in quick, satisfying death. If you are not dead, repeat as needed.
I got a gift for you. Take the hint.
Thankfully for you, eating a few seeds, will not result in instantaneous death. Your body is able to detox small amounts of the toxins, however, if you start popping them in your mouth like Lay's Potato Chips, (You can't just eat one.) you'll be unlikely to eat breakfast the next morning.
Here's one good rule to follow: Spit out those disgusting pits you slimy jerk.
Potatoes
"Here's something that doesn't have seeds! Perhaps it'll actually be interesting." - Murdered Victim
Have you ever heard of the fabled green potato chip? Even though it's mainly untrue, there's some truth to the back story. So yeah, it's fine to eat your green potato chip collection.
The actual truth behind the legend, is the green potato. Green potatoes indicate high concentrations of solanine poison. All normal potatoes contain this poison too, except in lower amounts. In order to be slightly affected by normal potatoes in any way, you'll have to eat almost five pounds of potatoes in one sitting. Sounds like my mashed potato frenzy at Thanksgiving dinner right?
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The poison can result in vomiting, diarrhea, and even paralysis of the entire central nervous system. If you have the option to, try not consume more than one hundred, five-pound bags of green potatoes at one sitting. (I know you can't help it.)