That particular version of "no backmark" North Carolina State Seal button was manufactured only between 1862 and 1865. (None are known to have been found in 1861 sites.) There was a version made by the Scovill Manufacturing Company of Waterbury CT in the 1850s but it always had a backmark, so that's not the version you found. Your version was issued to all branches of NC State troops (infantry, cavalry, artillery, etc), and to both officers and enlisted-men's ranks. (There was an officers-only version of pre-1866 NC State Seal button, but it is super-rare.)
And yes, based on where you dug it, it was probably on a Confederate soldier's uniform during the Battle of Bentonville. I suggest you hunt that field very diligently, because where you find one civil war Military button there are often more, plus other relics from that time-period.
I found this North Carolina button this morning in a bean field near Smithfield , NC. was hoping someone could shine some light as to what it is . I'm sure its confederate but was it infatry , calvary , officer etc and was it assigned to a certain regiment? The back of the button has no writing on it and the hook is still intact. The area I searched is supposedly where Sherman's army marched through after the battle of Bentonville headed towards Raliegh so it could have been possible this button was on a uniform at the battle of Bentonville among others
