Calm.com- an easy to use app/website that has guided meditations- I've used this a lot and love it
The Rubin Museum- they have weekly meditations and talks which are GREAT. if you're not able to make the actual meditation they post a podcast of the talk here. I personally love what Tracy Cochran has to say.
Nature- the park, your yard. Of course it'd be nice to go away to the mountains or the beach and let your mind wander through the myriad of visuals to offer, but I find that even sitting and looking at one beautiful tree or up at the sky can bring me piece of mind and remind me that I'm a part of the amazing thing called existence.