The 26-year-old model feels "physically sick" when she sees the fastenings and was left particularly traumatised when she hugged a friend without checking her outfit first.
She said: "I have a phobia of buttons - they make me feel physically sick. A girlfriend of mine once wore a pair of jeans with multicoloured buttons on the pockets. I was hugging her and grabbed her bum. I thought, `Oh my God, what`s that?` When I saw them, I went green."
Poppy loves her work as a model, and was particularly "overwhelmed" with happiness at a recent show because she thought the clothes were so beautiful.
Asked when she last felt really happy, she said: "At the Chanel show in December. I wanted to wear every look on the catwalk and felt overwhelmed by the whole experience. The Scottish reeling and the clothes were out of this world. I`d like to float around my house in one of those babies."
Though Poppy enjoys modeling, she worries she has now left it too late to embark on an acting career.
She told Grazia magazine: "I wish I`d gotten into acting earlier. I started modeling because I wanted to make money and then I really fell in love with it.
"But I forgot about what I`ve always wanted to do, which is make films, so I wish I had done it earlier. It`s never too late, I hope."