You need to go around them either until the foliage has yellowed or at least 6 weeks after flowering. Otherwise you will weaken and ultimately kill the bulbs. You will have some patches of longer grass for a while but they look fine if the rest of the lawn is trim. In fact you may find other plants taking advantage of the non mowing regime and have a show of wild flowers you weren't expecting.

if your goal.. is mowing the lawn.. as you state that is your NEED ... then mow the lawn.. and who cares what happens to them ..

the alternative is that when they start to yellow... you dig them up.. and that wont be fun... and plant them in a bed ... where your NEED will be fulfilled ...

a different way of saying what flora said.. was that after flowering.. they are using the green leaves.. to store energy in the bulb for next year ... if you do not allow them to store such ... then they will be weaker next year.. if not disappear altogether ...

define your NEED... and act accordingly ... but you cant have both.. as they are planted now ... and you can move them now.. and disturb the storage process ...

good luck .... did you inherit this with a new house???? .. if so.. get rid of them.. no need to cope with someone elses mistake.. when you have other needs ...

ken

ps: this is why planting them in the lawn.. is not the best idea... if you have tendencies towards the ultimate lawn warrior.. where grass rules supreme ... its a look that works better.. when your lawn is hundreds of feet deep.. and you can put them way the heck out there.. where you cant see the long grass .. and dont care ... IMHO.. it really doesnt work in suburbia ... not to mention.. in warrior mode... you cant use weed killers etc ... as these would be considered weeds to a grass-aholic ....

Thanks for the quick comments. I built my house on an old house place. There are several other flowers that have come up also, iris, spider lillies etc. I will try to cut around and might move them after they die down.