I'd absolutely consider gray and white for my own nursery someday. I just love the softness of it, and I think it's super easy to infuse color with this neutral palette. It's a modern and simple aesthetic that is also a classic.
Here's a green polka dot print in a subtle shade. I prefer a subdued version over a bright lime green because I think it gives enough of a pop without being obnoxious.
If simple gray and white is too boring for you, opt for this set which adds in a subtle touch of yellow. I like this as a gender-neutral alternative.
Price varies by piece $22 to $129.