CRJ-700 First Officer reported returning to departure airport after experiencing stabilizer trim anomalies during climb.

Narrative

I was pilot flying on this flight. All events leading up to the takeoff were normal. Shortly after takeoff; around 1000' AGL; I called for climb sequence (flap retraction) and lowered the nose to accelerate. As the aircraft accelerated; nose down trim was required. As I stepped the trim forward (nose down) I would relax a little bit of back pressure on the control wheel to sense the aircraft trim. It still required a lot of nose forward pressure and trim. After about 30 seconds of adding nose down trim; I voiced my concern to the captain that we may have an issue with the trim. I added more nose down trim and was watching the trim indication on our displays. It would display that nose forward Trim was being added; but on release of the trim switch on the control wheel; the indications would show nose up trim was being returned/added. This confused me and I had a difficult time trying to fly the plane and explain what was happening to the captain. He advised me to engage the autopilot to alleviate workload so I did. I told him I would feel better manually flying the plane so I could feel the different control pressures if this was a trim issue. Upon disconnecting the autopilot; I asked the captain to take the controls so he could feel what was going on. Upon transfer of controls he pressed his trim disconnect switch on his control wheel and advised I do the same. Between disengaging the autopilot and disconnecting the trim switch; the memory item for stab trim runaway had been completed. In the interest of passenger safety; I suggested requesting vectors and [requested priority handling] to return to ZZZ; as we had only been airborne for about 2 minutes. The captain agreed. We got immediate vectors back to ZZZ and landed without further incident. We taxied to the gate where maintenance met the aircraft to troubleshoot the problem. Crew scheduling then reassigned us to fly our next leg on the same aircraft but I realized I was pretty rattled from the event and felt it would be best if I was removed from any more flights that day. I coordinated with crew scheduling and my captain. I was taken off duty and given a hotel room for the night.Cause: I am unsure of the cause of this eventSuggestions: I am unsure of the cause of this event so I can't offer any suggestions on how to prevent this.