It's too hot now in zone 8 for peas. They like it cool. Depending on what state you're in, you might want to start them in February. Also, you have too many plants too close together in a container which gets hotter than if planted in the ground. Next time, plant peas in containers an inch or more apart and keep the pot itself (and the soil) shaded behind something that will keep the soil cool.

Best of luck to you.

Thank you so much -that was helpful! The weather here in Portland and been back and forth. We've had a few hot days lately for sure. Not normal.