John Jeavons (How to Grow More Vegetables
, 7th ed.) has incredibly detailed charts with information on possible Yield in Pounds per 100-square-foot planting area using Grow BioIntensive methods, which are described in the book, and many other points of information.
According to Jeavons--who has at least 30 years' worth of records to back him up--a 1st-year Grow Bio gardener could expect a 25-lb harvest, a 2nd-year 53 lb, and a 3rd-year 106 lb. These numbers are for fresh peas, not dried. The "dried" numbers are 4, 10, and 24, respectively.
However, the "Intensive" in "Grow BioIntensive" is a serious word. Another column in the chart is entitled "MAXIMUM No. Plants per 100 Square Feet." This name is followed by a small numeral 7 which represents a fairly complicated note on plant spacing.
In any case, the maximum number of pea plants in 100 sq. ft. using the hexagonal spacing and Jeavons' system 100% is 2,507. I think it's safe to assume that the harvest amounts are based on a very large number of plants; maybe not 2,507, but certainly a lot of plants.
We grew a few sugar snap pea plants in Spring 2008 and a few in Spring 2009. I just couldn't take the waste of shelling peas; throwing the pods into the compost just seemed wrong to me. The sugar snap peas (edible pods) went into mixed stir fries and were just terrific! I only harvested a handful at a time, but their character enlivened the whole stir fry, which consisted of kale, chard, bok choy, spinach, broccoli leaves, and the sugar snap peas.
You're in Sunset climate zone 14. Knowing this, and referring to the Sunset Western Garden Book
, will help tremendously in timing the planting, harvesting, and selection of successful varieties for your garden.
Sunset Zone 17, USDA Zone 9