One scary Halloween candy story is about the poisoned candies. There were rumors that some people would put harmful substances in candies and give them to kids on Halloween. This made parents very worried and they would carefully check every piece of candy their children got.
There is a story where a child received a candy that glowed in the dark. At first, it was exciting. But when the child started to eat it, it made a screeching sound. The more the child ate, the louder the sound got until it was unbearable. It was said that the candy was made by a vengeful spirit who didn't like the happy atmosphere of Halloween.
In a small town, there was a rumor that a deranged dentist on Halloween hated the idea of kids getting so much candy. So he would go around at night, disguised as a normal person handing out candies. But his candies were filled with a chemical that would make the kids' teeth ache horribly. When the kids woke up the next day with excruciating tooth pain, they realized there was something very wrong with the candies they got from that strange man.
One story is about a kid who got a piece of candy that had a strange symbol on it. When he ate it, he started seeing creepy apparitions everywhere. He was so scared that he ran all the way home and refused to go out on Halloween again for years.
You might try interacting with Candy Cadet in a friendly and engaging way. Maybe start by showing interest in what it has to offer and gently ask for a story.
You might find it at a local bookstore specializing in holiday-themed books. Sometimes they have a collection of Halloween stories, including those with silver covers.