[Bloody Sam Roberts]

fortunately, they're very easy to spot:

And easily confused with a Milk Snake which is not poisonous. Red touches yellow, kill a fellow. Red touches black, poison lack.

[Verginius Rufus]

The version I remember from when I was a kid went:

"Red and yellow, kill a fellow.
Red and black, friend of Jack."

Never found out who Jack was.

[drunknsage]

Its worth noting that the color patterns of coral snakes varies throughout the world and the red on yellow works only in parts of the US.

I come across them on occasion and they present very little threat despite being highly venomous. They aren’t in the least bit aggressive unless cornered with no way out. I occasionally find and remove them from my backyard with ease.