There are thousands! Here are a sampler:
Kabalas
Kayaker
Karmic
Kaput
Kanji
Try ki and ka.
Some Scrabble words that start with U are:upususeunderuncleurineuntoundounclearunnecessaryumbrellaurgentuglyusefulumberutilityunusualunguentuniversalupperundulyundecidedutmostunitunmanageable
Words starting with USHUsherUsheranceUsherancesUsherdomUsherdomsUsheredUsheressesUsheretteUsherettesUsheringUsheringsUsherlessUsherredUsherringUshersUshershipUsherships
effecteffigyefforteffuse
knowledge
avenue??
Axe.
There are no words that start with ZH, here are some words that start with z:ZacatonZaddickZaffarsZaffersZaffirsZaffresZaggingZaikaisZamarraZamarroZananasZandersZaniestZanyishZapateoZappersZappierZappingZaptiahZaptiehZarebasZareebaZaribasZealotsZealousZeatinsZebecksZebraicZebranoZebrassZebrineZebroidZecchinZechinsZedoaryZelkovaZemstvaZemstvoZenaidaZenanasZenithsZeoliteZephyrsZeppoleZeppoliZeroingZestersZestfulZestierZestilyZestingZeugmasZibethsZiggingZigzagsZikuratZilchesZillahsZillionZincateZincifyZincingZinciteZinckedZincoidZincousZinganiZinganoZingaraZingareZingariZingaroZingersZingierZingingZinkifyZinniasZiplessZiplockZippersZippierZippingZirconsZithernZithersZizzledZizzlesZlotiesZlotychZoarialZoariumZocalosZodiacsZoeciumZoisiteZombiesZombifyZonallyZonatedZonkingZonulaeZonularZonulasZonulesZooeciaZoogenyZoogleaZooidalZooiestZoologyZoomingZooningZootierZootomyZorillaZorilleZorilloZostersZouavesZoysiasZydecosZygomasZygosesZygosisZygotesZygoticZymasesZymogenZymosanZymosesZymosisZymoticZymurgyZyzzyva
ivy and ivory
tablet table
identify idiot
reject