Love this post! I'm on a similar journey, with a 20 mo. old. I'm a Christian but have found wonderful wisdom in Zen Buddhism and other religious practices. There is a Zen center about 20 min away from my house; I'll go sit in formal meditation for an hour every Wednesday. It has been a challenging and wonderful experience!
The meditation I encourage with my DS is mostly when we're having quiet time and reading books. I've asked him to take a deep breath when he's acting wild and I'm pretty sure he pretends he doesn't hear me ;) When we're reading, we'll both take a deep breath in between each line or when we flip a page. It's almost become a game, and definitely a bonding ritual.
Usually when we're going to bed, I recite Goodnight Moon and I'll take a deep breath between each word or sentence. Before he could talk, we were laying down in bed one night, and I was daydreaming about something we had to do the next day. He started taking slow, deep breaths on purpose and I realized he was asking me to tell him his story! It was so sweet!
Just some ideas, I'll sometimes incorporate breathing and mindfulness during eating, taking a deep breath and chewing slowly while we eat together, or if we are doing crafts or cleaning even, I'll breathe deeply and pay close attention to putting each handful of blocks into their basket. It ends up being this fun, calming thing to do together, and really brings us into the present (well, brings me into the present, anyway; I'm pretty sure my li'l Zen master is always there).
Also, I benefitted a lot from a book by Myla and Jon Kabat-Zinn called Everyday Blessings. A couple others I've read are Buddhism for Mothers and Momma Zen (from Shambhala Publications).
Anyway, it's nice to "meet" some mamas who are on similar paths!