I accidentally ate undercooked black eyed peas. Am I going to get sick?

You won't get food poisoning. Add water, stir and let them simmer some more. They'll be fine.

Probability is high that you are safe. Peas (and almost every other legume, vegetable and fruit) in 2018 are genetically engineered to be safe to eat directly after packaging. Also, they most likely have been sprayed with fungicides and pesticides. In triplicate, sulfuric acid (the stuff in your stomach) is so strong that it will destroy almost every other thing the first two didn't already eliminate. I'd bet you'll be fine.

don't worry, you may get a tummy ache, because they may be harder to digest

You'll be fine