Knee.
Knoll.
knife
knell
Would "knoll" satisfy?
One example of a warning sound starting with "kn" is a knell, which is the sound of a bell ringing solemnly, often to mark a death or funeral.
Some words beginning with KN:KnackKnackerKnackwurstKnapsackKnapweedKnarKnaveKnaveryKnavishKnavishlyKneadKneadedKneaderKneadersKneadingKneadsKneeKneecapKneecappedKneecappingKneecapsKneedKneeingKneelKneelingKneelsKneesKnellKnelledKnellingKnellsKneltKnessetKnewKnickerbockerKnickerbockersKnickersKnifeKnifedKnifesKnifingKnightKnightedKnighthoodKnighthoodsKnightingKnightlinessKnightlyKnightsKnishKnishesKnitKnitsKnittedKnitterKnittersKnittingKnitwearKnivesKnobKnobbierKnobbiestKnobblyKnobbyKnobsKnockKnockaboutKnockdownKnockedKnockerKnockingKnockoutKnocksKnockwurstKnollKnollsKnotKnotholeKnottedKnottierKnottiestKnottingKnottyKnowKnowableKnowingKnowinglyKnownKnowsKnoxKnoxvilleKnuckleKnuckledKnuckleheadKnucklingKnurlKnurledKnurling
It's called a knapsack.
winning
The Waring sound the begins with a Kn is called knell oxford dictionary states that knell is a warning sound
Rhymes with Rock beginning with R:RobRodRomRonRotRoz
Yes, as beginning rhymes and first syllable rhymes.
stagger