Py-O-My ads are all over the place in the 50's, and yet now you never see the brand. Yet it still exists, barely: Py-O-My/Kitchen Arts Foods was bought in 1968 by private label food manufacturer (i.e., generic/store label) Gilster-Mary Lee. The only Py-O-My product still available is the coffee cake mix, which G-ML sells online as a "Hard to Find" food item. I'm tempted to order it, just to see what the box looks like now, but you have to buy a case. The Internets offer no clues as to the meaning of "Py-O-My." They didn't sell pie crust mix, from what I can tell, so I'm stumped.
In addition to coffee cake and muffin mixes, Py-O-My also sold, in the 50's, brownie mix that came in its own disposable foil pan, and a "Puddin' Cake" mix (mix it, pour extra water over the top, and voila! It doesn't bake completely and you have goo at the bottom of the pan. Or, "pudding.").
What I find most striking about this image is the size of the muffins. Tiny by today's standards, this is what food looked like before America supersized itself. That's a normal muffin, folks; everything you see and eat today is too damn big.
On the other hand, candy bars have gotten a lot smaller over the years, so you can eat all of those you want. Happy Easter!