It's kind of hard to tell in this picture (curse you, winter drudgery, making it impossible to take photos outside!), but this cowl is a gorgeous olive green color that looks great with the bright mint.
I actually had my lovely friend Kirsten make this cowl for me more than two years ago when I saw a similar one on Etsy -- and I absolutely love it still and highly recommend her shop, Beatknits. She makes beautiful pieces that are really warm, and I love the little touches she adds (like the fun wooden button she sewed on this cowl).
Wearing shades of the same color (and then tying them together with neutrals) is an easy way to look polished. And, as I'm sure you've noticed, I wear these boots all the time. Taupe really does go with everything.
What's your favorite shade of green? I'm totally loving mint -- although emerald is the Pantone color of the year, so I may have to invest in that soon, too.