Is there ANY green paint I can use on cement blocks for my backyard?

I imagine you can get these paints in any color you want, you need to use a concrete primer and then you can use a concrete paint (or even concrete floor paint). You can get these at most home improvement stores.

Any outdoor concrete paint can be used

Any exterior paint would work

Home Depot has Sure Step Pine Green Satin and Behr has Green Adirondack 1 part epoxy concrete paint.

You want environmentally friendly (aka green,low voc), paint for cement blocks? Yes there is. All major paint brands have a "green" line. Visit a proper paint store for best selection and the proper assistance. I repainted my mom's house about 10 years ago when green products were still very expensive. I used Dunn Edwards.

yes, most lines have a 'green' option now...

you might also look into 'earth pigment' types of stains.