Back in 1986, Ted Kooser wrote a poem for Valentine’s Day, printed it up on a postcard, and sent it to women he knew. He did this the next year, and the next, adding a name or two, each year shipping the cards over to Valentine, Nebraska, for the postmark. After two decades of this sweet, facetious nonsense, he decided to call it quits—by then the mailing list had grown to 2,600 names and the postage exceeded the annual budget of Omaha. Valentines collects these poems, pieced out with black-and-white drawings of farmhouses, prairie landscapes, and an alarming number of dead trees.[1] Perhaps they’re just waiting for spring; but it does seem odd to illustrate a book of love poems with a lot of leafless shrubbery.

Joseph Brodsky wrote a poem every year at Christmas; more poets might adopt a holiday, preferably an obscure one like Liberty Tree Day or National Mustard Day,...