there are many, example;
mime
mine
mike
mick
mini
mice
miss
mild
mile
mist
milk................+ more
Mire is a 4-letter word for bog that starts with "Mi"
egis
gas
east
hums
Aper
Some four letter words beginning with Y are:yardyarnyawnyearyellyelpyokeyolkyouryurt
yarn, year, your, yaks
span
ibex idea idol into item
x-ray
ankh