I haven't looked in depth into the specific famous cases of jury-nullification, but there were several instances where historians and law scholars have identified very influential trends of mass jury-nullification, when the juries of an area were likely to acquit defendants of a certain type of crime. My examples here are in no way a definitive list of these actions.

One of the most famous examples of this was reactions to the Fugitive Slave Acts in the North. Especially around New England, juries refused to either indict or convict those accused of illegally helping slaves escape to Canada. Under federal law, the accused slaves didn't get a jury trial, they were subject to very one sided hearings where they weren't allowed to speak on their own behalf and weren't required to have legal representation. Some states, most famously Vermont, extended rights to those accused of being an escaped slave so that they must be tried by jury trial. So there was jury nullification in trials for the mainly white abolitionists who were involved in helping hide or transport slaves to Canada and for those accused of being fugitive slaves themselves.

Obviously this was a wedge between North and South. The Fugitive Slave Laws were supposed to help prevent abolitionists from helping slaves escape, but you have both states nullifying the laws in various ways like switching the hearings for slaves into jury trials, and the instances of jury nullification. Maybe someone with more knowledge of the time period can more specifically state how jury nullification affected the politics of the era, but the reactions to the state laws nullifying the fugitive slave act are easier to see. South Carolina's proclamation for secession mentions the failures of federal and northern state governments to uphold the Fugitive Slave Act, not the jury nullification.

While I won't go into detail, I think mentioning vigilante violence of the 19th century probably should be paired with a discussion of the fugitive slave acts. The debate over nullification is pretty politically charged even today. If you want to talk about the good instances, you downplay the failure to convict lynchers and highlight the abolitionist efforts. Alternatively you could focus on jury nullification as the literal will of the mob by connecting it to juries failing to convict perpetrators of racial violence against minorities such as blacks and the Chinese.

"“Slave Law” versus “Lynch Law” in Boston: Benjamin Robbins Curtis, Theodore Parker, and the Fugitive Slave Crisis, 1850-1855" Dean Grodzins

Lynching in the West : 1850-1935 Ken Gonzles Day

Driven Out: The Forgotten War Against Chinese Americans Jean Pfaelzer