My son is 3.5 years old, also doesn't like to go to school. We all have to leave home all at once and tell him that he has to leave for school as no one will be staying home with him. He has been crying for 9 months for not going to school in the morning. Once is over the long weekend or holidays, he also cries and doesn't want to go to school.
I tend not to have too much toys at home for him and make him feel that going to school is more fun than staying home by himself.
you can try give your daughter a small photo of you or sth. Tell her that the thing is just like mom, staying with her at school. See if this will comfort her and stop crying when you leave her at school.