The present disclosure relates to a valve, a method for forming a valve, and a package. The valve is made of at least three layers—a first exterior layer (i.e., a base layer), at least one interior layer (i.e., a bubble layer), and a second exterior layer (i.e., a channel layer)—and an attachment section located on each of at least two of the at least three layers. A bubble is formed between two of the first exterior layer and the at least one interior layer, and the bubble includes an enclosed material. A channel is formed between two of the second exterior layer, the at least two interior layers, and the first exterior layer, and the channel includes an inlet and an outlet. A physical characteristic of the bubble biases the channel towards a closed position that restricts flow of contents from the inlet to the outlet.