Recipe books often specify Dijon mustard in their list of ingredients. This iconic French product is made from vinegar, water, salt and mustard seeds, but mustard is hardly grown in France any more, much less in the Dijon area. The prepared mustard paste manufacturers of France source 90% of their mustard seed from Canada.
The reason for this seems to be that after the end of the Second World War, with the introduction of the Common Agricultural Policy, farmers found mustard was no longer profitable. The crop did not receive an EU subsidy, and so they switched to growing other things.