This is Swiss chard.
It is not, as I mistakenly believed last year, rhubarb. Although, in my defense, rhubarb looks suspiciously like Swiss chard. The purple stalks! The broad green leaves!
Thinking it was rhubarb, one year ago I tossed the (perfectly edible!) leaves and used the stalks to make "rhubarb" crisp. Which tasted like it was made from celery. Ugh.
Aside from learning what chard actually looks like, the most useful thing I've learned about it since then is that its leaves can be substituted for spinach in pretty much any recipe. It's not too tough and has a very mild flavor.
We used some of our first chard of this summer in bee-bim bop. I always enjoy this meal, even with all the pots and pans it dirties.
Believe it or not, this recipe came from a children's book. One day The Boy picked up
Bee-Bim Bop! by Linda Sue Park at the library. It's a bouncy, rhyming tale of a little girl happily helping make her family's dinner of bee-bim bop (which the book translates as "mix-mix bowl"), a Korean mixed dish of marinated beef, vegetables and fried egg.

A recipe follows the story, with instructions divided up for "you" (the child" and the "grown-up". After many, many readings of the book, The Boy was excited to taste bee-bim bop himself. It was a huge success! Love the marinade for the meat.
It is a time-consuming, multi-pan recipe. And I make no claims that I'm doing authentic Korean cooking here. But bee-bim bop has easily slipped its way into our regular stable of meals.
Recipe below; printable version
here. Check out
the book for a kid-inclusive version!
Photo credit (rhubarb): Sandy Austin