Grandma B put together cowboy/cowgirl outfits for the kids for Christmas. She also found each a cowboy book. M2's book, Cowboy Small, mentions the song "Home on the Range" and for a while it made a nice lullaby. I can't use it anymore because he belts it out as loud as he can if I start singing it.
Here is a duet - they each sing the first part on individually and then finish up together. The look they are giving each other toward the end always melts my heart.