I'm watching the movie for the first time today. Quite good and it largely followed what's in the novel which I read back in high school. I really loved it. When you think about the story there are some really horrifying and twisted things in it. I've probably read Flowers at least a dozen times and it's one of the things that I'm sure has contributed to what I write.
The grandmother locks the kids away in a bedroom and an attic. They can't get out unless they die which the grandmother feeds them arsenic to help achieve it. Every morning she would take pure arsenic, mix it with powered sugar and sprinkle it on the morning donuts. The kids mother only wants what she wants. She ignores the kids also. Certain passages from the Bible are used to justify everything which helped change some of my viewpoints at an early age.