Peas and beans have been used as a source of bread making flour for centuries. In the Far East, many flat breads are made from pea flour. Also in Medieval and Tudor times, bean flour and pea flour were used as a fall back when wheat grain was scarce before the harvest. There is also a good market for pulse flours as a gluten free additive or in making instant soups and stocks.
The dried seed of pulses will keep for a very long time if they are kept dry. However, when pulses are milled into flour they have variable keeping properties and the flour is usually milled for immediate use. Green pea flour and Yellow pea flour will keep for a few weeks once milled, but will deteriorate due to enzyme activity and oxidation. Such flour in a modern kitchen can be kept cool in a refrigerator, or frozen to extend its shelf life to years.
Finding bean and pea flour is a challange. In many cases it may be easier to buy the dried pulses and grind the flour.