I find myself wondering about alliterative story titles.  If it had been not a princess but a countess then I suspect she would have been traumatised by a cauliflower rather than a pea.

See Aarne-Thompson classification number 704. Also see this.

↓ Transcript
Pea couldn't sleep at all. Through a dozen slabs of marble and hardest obsidian he could feel something soft and yielding. By the time morning arrived he was bruised all over.