MOSFET - OPAMP circuit
There are a few things:

As Dave mentions, you are setting the current higher than the supply can provide, therefore the voltage at R1 will never reach 3.7V. So set the voltage lower or increase the set resistor. 

A couple of other things about SPICE:


You are using the basic ideal opamp model, so it will ignore supply voltage and drive as high as it can (e.g. 297kV if that's what is necessary for 3.7V at the inverting input. It could be infinite if it can't achieve 3.7V at any voltage, only limited by the FP range in SPICE) A better model is "Universal Opamp 2" (you can set various parameters such as gain, bandwidth, etc, with this one), or you can use one of the many LT opamps. These would do what would happen in real life, simply hit the supply rail.  
Right click on the MOSFET and select a real model from the list. Otherwise you are again using the basic model. This is what @Abdullah was referring to.  


EDIT - here's an example circuit:



Simulation with the input swept from 0 to 5V: