Half-H bridge or low-side MOSFET for PWM motor control
If this is a simple brushed DC motor with just two connections, then yes, you can tie one lead to power and use a low side switching element on the other.  Don't forget to put a reverse Schottky diode accross the motor else the switch will get destroyed from the high voltage pulses.

At only 12 V, you can find N channel FETs that will switch well enough directly from a digital signal.  These are often called "logicl level" FETs.  In that case you don't need a FET driver.

Another possibility is a NPN as the switch.  That is easy to drive from low voltage logic, but turning off a saturated bipolar is always a bit tricky.  It depends on how fast you want to go.  For a normal motor drive PWM frequency of about 25 kHz, it should be fine.  However, unless you are using unusually low logic levels or the micro has a weak output drive, I'd look at logical level N channel FETs first.