We had cattle when I was growing up and occasionally put out salt blocks for them. They were about 50 pounds each and came in different “flavors.” A plain salt block was white, a mineralized salt block was kind of chocolate colored, and a sulfur salt block was yellow (the sulfur was supposed to release through the cattle’s skin to help keep flies away).
Possibly, but I think it’s more likely inspired by a number of books published in the early 70s that some U.S. schools banned from their libraries. A few of these books were stories about animals, and Schulz might have decided to make a connection with the “Bunny-Wunny” books he’d used in the strip before.
She just wants to see it on her schedule, lol.