Here's the background for this holiday. I'm intrigued by these random holidays, even though I suspect that they are the work of industry groups. Through the Dog Lovers group on Linked In, I received this link.
Good information. Jeff had told me that only peanuts were good for dogs because they are not nuts, but legumes. Peanut butter was one of Spike's first treats because he was a vegetarian before he came to live with us. (We thought that was unnatural, and changed that.) He still loves peanuts and peanut butter, as do Jeff and I.
The nut article included a link to this article, which is a good source. We're fine with more of Spike's favorites: carrots and apples.