I'm just starting to teach mindfulness this year, mostly as classroom guidance lessons, so this page will be a bit skimpy to start off. However, I bought the MindUp curriculum from the Hawn Foundation last summer and am loving it so far. I was able to find both the K-2 book and the grades 3-5 book for a total of $30 from Zulily.com, though I believe the regular prices aren't a whole lot higher than that. It's a lot of great stuff for a reasonable price.
Here are some of the things I've found in my on-line search for activities that I can use to supplement the MindUp lessons:
-Mindfulness mantras (e.g. "be the pond") & the pond story (p 13-14)
-Make a mindful breathing wand
-Take a rainbow mindfulness walk (excellent for kids who find it difficult to sit still)
-“Human camera” partner activity
-Trying on different “shapes:” mindfulness of mood and posture (good for also reinforcing learning about nonverbal communication).
-Collection of lessons and resources for teachers
I made a poster of the three parts of the mindful brain, which you can grab for free here in my TpT store.