I can only speak about one big event, and that's the biggest riot in US history: the mob that formed to kill the imprisoned members of the Matranga family. The Matrangas were the first Italian mafia family in American history, as far as I know. The current police chief David Hennessy was unusually tenacious in trying to clean up street level corruption, and next thing you know he ends up shot in the street. Several of the Matrangas are put on trial. There's a good case for them committing jury tampering, given that the defendant LEAST likely to be guilty was the only one who ended up with a guilty verdict(he was just some powerless Italian fruitseller who was there at the wrong time, as far as can be told).

When the verdict was announced citywide, a mob formed that was so big that it overtook the police force, overtook the jail, and slaughtered many of the prisoners inside(the head Matranga, ironically, actually survived by hiding under a mattress). This means even people just awaiting trial, and of course, especially if you seemed Italian.

This was a HUGE deal at the time. The United States government actually had to pay money to Italy in apology because Italy had completely severed diplomatic relations. Italians years after in NOLA would be hounded by people saying in a faux-Italian accent, "Who kill-a the Chief?"

But New Orleans is also the only city in the South at this time with a large Italian population. So for the rest of the South, if there was a lynching other than this, I can't say if it was just usual hatred of someone different from you, the smear of the Hennessy trials, etc. As far as I know, there's not much information on anti-Italian violence in the South besides the Hennessy trial lynch mob.

Edit: I did a bit of Googling--it's not my area, so I won't say much, but for Jewish lynchings, you might want to research the name Leo Frank.