Air valve for a fillable poly bag

A fillable poly bag with an air vent valve, comprising:

• a poly bag having front, rear and side panels with a top and bottom, a filling chute beginning at the top of the bag near one corner and extending toward the other top corner, an air vent valve in the poly bag near said one corner and automatically closeable as the bag fills, said air vent valve including openings in the poly bag itself near said one corner, and a flap separate from the poly bag inside the poly bag adjacent said openings underneath the side panels therein movable from a first position permitting air to escape through the poly bag openings and a second position blocking air flow through the openings, said flap being automatically closeable upon filling as the filling material engages the flap and urges it against the side panel.