But:

calf-calves

dwarf-dwarfs or dwarves

elf-elves

half-halves

hoof-hoofs or hooves

knife-knives

leaf-leaves

life-lives

loaf-loaves

scarf-scarfs or scarves

self-selves

sheaf-sheaves

shelf-shelves

staff-staffs or staves (sticks or musical ones)

thief-thieves

wharf-wharfs or wharves

wife-wives

wolf-wolves

chiefs

cliffs

cuffs

diffs

gulfs

huffs

muffs

oafs

puffs

reefs

roofs

safes

surfs

tiffs

toffs