I planted Tom Thumb peas in a container (from seed) in early March. There are about 8 plants in a 15-inch diameter pot. The lower leaves are now yellow, with some of the leaves turning a dried out light brown color. I think it might be fusarium wilt, based on descriptions of the disease, but am not sure as I can't find any pictures that match. I used Miracle Grow Organic Potting mix. Thanks.
It sounds like you might have a soil problem. I never plant my peas that early, but wait until the end of March as they don't like cold (just cool), wet soil. Also potting mix is not really adapted for garden plants. The garden soil mixed with some regular soil usually works better. Have you gotten any peas yet?