If they have a 90 day probation am I an employee at will and either they or I can quit without cause and I would not be held to my 30 day notice?
Employment / Labor Attorney
You can quit your job at will. Although, for purposes of goodwill, I'd suggest giving notice. If they terminate you, they need to follow what the contract says. If they fire you with no notice, you'll probably want to have an employment lawyer review your contract to see if you have any rights to be paid for the notice period.