Containers formed of a flexible sheet of material capable of being sealed for closing off the interior of the container from the ambient atmosphere. The sheet material is resistant to tearing and includes an inner surface and an outer surface. The container comprises a mouth portion including a peel strip or layer fixedly secured to the inner surface of the material and extending substantially the entire length of the mouth portion, with adjacent portions of the peel strip or layer being in releasable engagement with each other. The engagement forms an air-tight interfacial seal at the mouth which is readily openable by peeling the engaging portions of the peel strip or layer from each other to provide ready access to the interior of the container without tearing the sheet material forming the container. Thus, the container can be readily reclosed by conventional mechanical means, such as folding, tin ties, etc.Some containers are formed in accordance with the method for applying the peel strips transversely across a web of sheet material and heat sealing the strips to the material at longitudinally spaced locations and thereafter severing the web into sections which are formed into the container. Other containers are formed by use of a peel layer on the entire inner surface of the container. The peelable interfacial seal for such containers is formed by heat sealing the same within a desired temperature range. The remaining seams of the container are permanent and are formed by heat sealing the same at temperatures in excess of those used in making the peelable seal.