I believe snow peas grow best in the cooler months and they should be picked when young so the pods are tender/crunchy. I do save some of my larger seeds for the winter sowing.

i thought i was picking them young... what size would u pick? is 6-7mm already too mature? thx!

You either let some of the pods get too old, you didn't pick them when you should have, or you have some shell peas mixed in. Snow peas, you pick them when they are still flat with little bumps.

Are the flat pods with tiny peas edible? If the pods with huge peas are inedible, you could take out the peas and just eat the peas,

Peas are a cool weather crop, and it is normal for the plants to yellow and eventually die in Summer heat, but sounds like you are in the North. Canada?

If you don't like them, you should probably try something else and not save the seeds.

6-7 mm is really small for a snow pea, did you perhaps mean 6-7 cm? Or were you referring to seed size?

Length is not an indication of harvest time, since different varieties can be different sizes. Weather too can alter the size at which a snow pea should be harvested; they mature more quickly, and are usually smaller, in hot conditions.

As Robert mentioned, snow peas should be picked while still flat, before the seeds have begun to enlarge. The toughness mentioned could be due to over-maturity, or to heat stress on the plants. It is important to keep the plants well watered & as cool as possible in hot weather. Mulching around the roots helps for both. It also helps, if you live in a hot climate and/or plant late, to plant snow peas (and peas in general) in locations where they will have afternoon shade.

One other note on toughness/stringiness. Some snow peas will need to be "stringed", just like older varieties of snap beans. Peas which have unpleasant amounts of fiber may turn out to be very pleasant once stringed.

The snow peas I used to grow were the thicker kind (still tender). Which kind are you referring to........is the pic on the package of flat snow peas or the fatter ones? Is the company you bought them from reliable? Have you bought from them before?