There are several different types of black snakes with white rings.
I'll list those that I know of:
Death Adder
Stephen's Banded Snake
Bandy Bandy
California Mountain King Snake
Long Nosed Snake
I can't really think of anymore right now, but try typing these names into Google image search and see if you recognise any of these.
its a Black & White Desert Phase California Kingsnake
The red-bellied black snake, which is native to eastern Australia, is black with a distinctive pink-red belly.
the Australian brown snake even tho it ain't brown prob a relative, also known as easten brown.
black snake
Sea Kraits are white with black stripes. Or black with white stripes if you like to look at it that way.They're a sea snake, highly venomous, but only aggressive when provoked repeatedly.King snakes are also black and white, striped. They are non-venomous, land based and eat other snakes.Hope this helped!
the worst kind
If the stripes are light in color, maybe even off white it could be a CA king snake.
A ring-necked snake, a small snake that eats invertebrates such as slugs and worms.
It could be a juvenile so you wont be able to know. Do you know where it's native or where it was seen?
coral snake
Sounds like a killdeer.
It doesn't matter what kind of snake it is, all snake droppings look the same. When fresh they are small black balls and maybe some fur, drifting among a white paste and clear to yellowish, gooey liquid. When stale all you see is some crusty white stuff and crumbly black balls and maybe some fur.