The ones etched into my memory.
I started cooking and baking young. When I was around 9, I made eggnog. Then, the recipe said you could warm it a little. So, I did. I warmed it a little too much and ended up with scrambled eggnog.
At around 13, I baked some cookies for my dad who drove semi truck across the country. I didn't have any eggs and found some kind of powdered egg substitute in the cupboard - it had bugs in it (I'm thinking like a flour weevil). I threw it out. Made the cookies with no eggs. They turned out paper thin with lumps of chocolate chips. He ate them anyway and said they were the best.
A few years after that, I made some apple pies. I grabbed the cinnamon and sprinkled it all over the apples. Well, come to find out cinnamon and chili powder containers look very similar.
I know I've made fails since then, but I just know how to cover them up better. Like a bday cake for my son that was supposed to be a layered cake, but wouldn't come out of the pan. Oh look I made you a volcano cake!

Turns out kids love volcano cakes.