You have most likely got pea moth maggots . Happens frequently at this time of year. The non-maggotty peas should taste normal though.

Below is a link to an article that explains more.

I now start my peas as early as possible in the year to have most harvested before the moth strikes. Everything harvested in June is clear, after mid-july trouble starts here and I need to pick out all the bad ones. The dates may be different in your location of course.

Here is a link that might be useful: Pea Moth