In the top photo the peas are well past their optimum picking size. Even for shelling peas they will be mealy and low in flavour and for edible pods they are a goner. The lowest pods are the oldest on the plant and that is why those are now over mature. The yellowing is normal for pea vines getting beyond their prime. Peas only produce a few pods from each plant and on most varieties they don't mature all at once. So you have to start picking as soon as a few are ready. To get a decent crop you need a lot of plants.

They are sweet & tender and not mealy. They just grew that way initially. They never looked like the pic on the bottom then became ribbed.

Well in that case I'm stumped. All the peas I grow always start out flat and swell. If they bulge it's a sign to me that they have not been picked soon enough. I've never come across a pea which produces full size peas immediately without going through the flat pod/embryo pea stage. Are you sure you didn't just overlook the flat stage?

Perhaps maybe they were lacking water when they first started setting pods? That's about the only other thing I can think of. I would have agreed with floral if you hadn't left the follow up comment.

Rodney

Exact same problem here with my peas! Would love to diagnose.

My peas are doing weird things now and I have written it off as heat stress on dying vines. They probably shouldn't still be alive at all, honestly I think I am lucky to still be eating fresh peas.