You can legally depart a field with no weather reporting under 135, with no weather reporting available, as long as you are departing VFR.
You can then obtain your IFR clearance airborne. You can go into a field 135 with no weather reporting as long as it is VFR. Who determines this? Well, like you said another pilot or someone compotent enough to give you a reliable observation.
Pilot- Commercial rated or ATP, how can a student give you a reliable report.
Or Billy Bob, but the catch is he has to see it on a weather computer, for instance if the broadcast is not working, but the machine is, he could read it to you. But he cannot say he sees 2 cows down the street at his moms house which is about 2 miles away.