Are you looking for dark greens, lighter greens, grayed greens.?
I have Powell Buff in my kitchen and my family room is Hampshire Gray by BM which is a deep olivey green. I also have Wethersfield Moss which is kind of dark. Some of the Benjamin Moore grays under the Historical section are actually green and look nice with Powell Buff, also a historical color. Nantucket Gray is one of my favorite greens when it's up on the wall. There are so many that would look nice with the Powell Buff. Powell Buff is such a nice color.