A dispenser for a liquid or semi-solid material includes a container having a valve element at one end and a piston at the other. The valve element includes central and annular portions, the annular portion forming a good seal with the interior of the container and the central portion having a plurality of resilient flaps forming a valve. The dispenser is easily assembled because the valve element may be placed in the container without special tools or retaining structure, and the valve element is retained in place by the material. The valve element includes an annular sealing portion that flexes outwardly against the interior wall of the container during dispensing of the material. The central portion having the flaps is relatively thick to provide good restoring power to the flaps, and it is recessed from the front wall of the valve to provide space for the flaps to open when the valve is in contact with the front wall of the container.