The Pinterest post is here: http://www.pinterest.com/pin/368802656955584448/ which points to this site: http://ortsov.com/patterns-for-crochet-afghans/ which points to a site owned by Kim Guzman. I looked at her website and blog, and did not see the pattern or a link to it. So, I emailed her with a pic of the afghan and the link that pointed to her site. She got back to me quickly saying that it was not hers, and that it was a horrible website using the name of her website so that could make money from Google Adsense by making money off the name of her website. Back to square one.
I'm thinking it's from a pattern book or magazine. If it's from a magazine, it will probably take a small miracle to find it.
Thanks for helping!