Common Words:
* Psalm
* Pneumonia
* Psychology
* Pshaw
* Receipt
* Psychology
* Psychic
Less Common Words:
* Knapsack
* Corps
* Raspberry
* Sceptical (British spelling)
* PT (Physical Therapy)
* PhD (Doctor of Philosophy)
Note: The letter "p" is often silent when it appears before "s" or "t" at the beginning of a word.
Let me know if you'd like more examples!