Common words:
* Kick
* Keep
* Know
* Kind
* Knife
* Kite
* King
* Kiss
* Knee
* Knock
Less common words:
* Knave
* Knick-knack
* Kaleidoscope
* Kiosk
* Kilometer
* Karma
* Ketchup
* Kiwi
* Knapsack
* Keyboard
Words with a "k" sound but a different spelling:
* Cat
* Can
* Come
* Cloud
* Cough
Let me know if you'd like more words, or if you have a specific category in mind!