The easiest headboard solution we know of? A textile panel hung on the wall (either draped on a wall-mounted curtain rod or simply nailed to the wall).
Above: A swath of indigo-dyed cotton serves as headboard, image via Slow Fashion House via Style Files.
Above: Two textile panels in an Australian bedroom by Phorm Interiors.
Above: A Moroccan wedding blanket as headboard; photo by Polly Wreford.
Above: A 20th century Syrian silk shawl draped on a curtain rod, photographed by William Abranowicz for Real Simple.
Above: Tarps hang above the beds in lieu of traditional headboards at the Base Camp Hotel in Tahoe, California.
Above: William Abromowitz photo, via Real Simple.