A blank of sheet material for forming a polygonal container includes a bottom panel, two opposing side panels each extending from a side edge of the bottom panel, and two opposing end panels each extending from an end edge of the bottom panel. The blank also includes a foldover panel that is configured to lock the container in at least a partially formed position. The blank further includes a reinforcing panel assembly that includes an outer reinforcing corner panel extending from the first side panel, an outer reinforcing end panel extending from the outer reinforcing corner panel, an inner reinforcing end panel extending from the outer reinforcing end panel, an inner reinforcing corner panel extending from the inner reinforcing end panel, and an inner reinforcing side panel extending from the inner reinforcing corner panel.