Lots. Probably the most famous and historically important incidents happened during the ("bleeding") Kansas border war.
Congress made a deal where Kansas would be allowed to vote on whether or not to allow slavery when it entered the union. Most of the territorial settlers at this time came from northern areas and had little interest in slavery. However, the slaveholding states felt creating more of them was vital for their survival. One of them (Missouri) was quite close to hand. Politically motivated violence between the two soon followed.
The "Free-State" town of Lawrence, KS was sacked by a "posse" of 800 pro-slavery settlers on May 21, 1856. In retaliation (and disgust at the non-violent political tactics of his fellow Free-Staters), John Brown formed his own company, and massacred 5 pro-slavery settlers at Pottawatomie Creek.
4 months later a gang of roughly 400 Missourians attacked the Free State town of Osawatomie. John Brown's gang tried to defend it with about a tenth of their manpower, but was brushed aside. The town was looted and burned.
There are some intriguing tales from my own town's history. Tulsa was technically (iow: Legally) in Creek territory prior to statehood. One particularly prominent Creek family was the Perrymans, who had a large ranch south of town. Its difficult right now to find anything negative about them online, but I hear a lot of stories about how they didn't particularly respect the law of the white settlers in Tulsa, were powerful enough to get away with that, and some interesting "exploits" that would often ensue. I think the most interesting one I heard was a tale about a local minister who had the misfortune of saying something during a sermon that one of the Perrymans felt was a personal attack on his wife, and found himself challenged to a duel (there was no option of not accepting)*
* - I believe there are still a fair amount of Perrymans around these parts, so I should hasten to add that I am quite sure they are to a person fine upstanding citizens.