Online Ceramics is a clothing company founded in Los Angeles, California in 2016 by Alix Ross and Elijah Funk. Many of their designs are tie-dyed by hand, and feature images and sayings associated with the musical act the Grateful Dead.

Shortly after John Mayer started performing with Dead & Company, the current iteration of the rock band the Grateful Dead that features some of its surviving members, fans began sending him T-shirts. “These really thoughtful packages,” he recalled recently, “like welcoming me to the neighborhood.”

The Grateful Dead has a rich history of bootleg merchandise made and sold by its obsessive followers. But one shirt among the gifts sent to Mr. Mayer stuck out from the rest. It featured a blooming rose and bones and came from two designers based in Los Angeles named Elijah Funk and Alix Ross, who ran a small business called Online Ceramics, which trafficked not in clay vessels but T-shirts and accessories.