A valve configured to control flows of fluid through the valve, the valve comprising: a valve opening formed in a first wall, wherein the first wall separates a first body of fluid on a first side of the first wall from a second body of fluid on a second side of the first wall; a member pocket formed through a second wall, wherein the second wall runs transverse to the first wall, wherein the member pocket passes through the second wall from a front opening in the side of the second wall facing toward the valve opening to a rear opening on a side of the second wall opposite the valve opening, a first protrusion formed at or near an edge of the front opening of the member pocket, the first protrusion protruding inwardly into the member pocket toward the rear opening, the first protrusion being shaped to form a cavity between the first protrusion and the inner surface of the member pocket; a second protrusion formed at or near an edge of the front opening of the member pocket opposite the first protrusion, wherein the second protrusion protrudes from the inner surface of the member pocket toward the first protrusion; and a valve member formed substantially wholly from a flexibly resilient material, the valve member comprising: a member body configured to be seated within the member pocket, the member body comprising a wedge and a slot, the wedge being configured to rest in the cavity between the first protrusion and the inner surface of the member pocket, the slot being configured to receive the second protrusion therein such that the seating of the wedge in the cavity and the reception of the second protrusion into the slot hold the member body in place within the member pocket; and a valve flap that extends from the member body to cover the valve opening on the first side of the valve opening such that flows of fluid from the first body of fluid to the second body of fluid are substantially prevented by the valve flap, wherein the valve flap is configured to resiliently flex away from the valve opening to permit flows of fluid from the second body of fluid to the first body of fluid. a valve opening formed in a first wall, wherein the first wall separates a first body of fluid on a first side of the first wall from a second body of fluid on a second side of the first wall; a member pocket formed through a second wall, wherein the second wall runs transverse to the first wall, wherein the member pocket passes through the second wall from a front opening in the side of the second wall facing toward the valve opening to a rear opening on a side of the second wall opposite the valve opening, a first protrusion formed at or near an edge of the front opening of the member pocket, the first protrusion protruding inwardly into the member pocket toward the rear opening, the first protrusion being shaped to form a cavity between the first protrusion and the inner surface of the member pocket; a second protrusion formed at or near an edge of the front opening of the member pocket opposite the first protrusion, wherein the second protrusion protrudes from the inner surface of the member pocket toward the first protrusion; and a valve member formed substantially wholly from a flexibly resilient material, the valve member comprising: a member body configured to be seated within the member pocket, the member body comprising a wedge and a slot, the wedge being configured to rest in the cavity between the first protrusion and the inner surface of the member pocket, the slot being configured to receive the second protrusion therein such that the seating of the wedge in the cavity and the reception of the second protrusion into the slot hold the member body in place within the member pocket; and a valve flap that extends from the member body to cover the valve opening on the first side of the valve opening such that flows of fluid from the first body of fluid to the second body of fluid are substantially prevented by the valve flap, wherein the valve flap is configured to resiliently flex away from the valve opening to permit flows of fluid from the second body of fluid to the first body of fluid. a member body configured to be seated within the member pocket, the member body comprising a wedge and a slot, the wedge being configured to rest in the cavity between the first protrusion and the inner surface of the member pocket, the slot being configured to receive the second protrusion therein such that the seating of the wedge in the cavity and the reception of the second protrusion into the slot hold the member body in place within the member pocket; and a valve flap that extends from the member body to cover the valve opening on the first side of the valve opening such that flows of fluid from the first body of fluid to the second body of fluid are substantially prevented by the valve flap, wherein the valve flap is configured to resiliently flex away from the valve opening to permit flows of fluid from the second body of fluid to the first body of fluid.