That looks like a variety of Magnolia. Not sure which one. Most likely it is Magnolia grandiflora or Magnolia virginiana. There are several others listed in Florida but are confined the the panhandle and are listed as rare.
I agree with Horntoad. It does have the look of Magnolia. Do you have a pic. of the whole plant? A pic. of a bloom could be most helpful also to narrow it down.