can we use a full bag of Organic Rye flour which was sold in Chametz before Pesach?

Shalom, Thank you for writing to us. Chametz that was sold to a non-Jew over Pessach is permitted after Pessach. There are some people who question the validity of the sale, and therefore refrain from eating Chametz that was sold. However, that is not the normative opinion, rather a stricture that is not widely accepted. In any case, there is a great likelihood that the flour in the question may not be Chametz at all. In short – the flour is perfectly acceptable. Blessings.