Wallboard rhymes with:
billboard, aboveboard, baseboard, billboard, blackboard, cardboard, checkerboard, chessboard, chipboard, clapboard, clipboard, containerboard, dartboard, dashboard, fiberboard, fibreboard, fingerboard, floorboard, hardboard, headboard, inboard, keyboard, linerboard, mopboard, onboard, outboard, overboard, paperboard, pegboard, plasterboard, pressboard, scoreboard, seaboard, shipboard, skateboard, smorgasbord, snowboard, springboard, storyboard, surfboard, switchboard, washboard
Wallboard sounds like:
walbert, walford, walfred, wallpapered, welford, wilbert, wilfert, wilford, wilfred, wilfreda, wilfredo, wilfrid, wilfried, willeford, willford, williford, wohlfarth, wohlford, wolbert, wolfarth, wolfert, wolford, wolpert, woolford