Gungo peas (aka pigeon peas) is actually a lentil. It's called toor dal in Indian.
http://en.wikipedia.org/wiki/Pigeon_pea
Green peas are the frozen (rare to see fresh peas in the US) bright green peas.
Green peas will work, but I think a better substitute will be a different type of dal or lentil or even kidney beans (small size)
for texture.
SIMPLE JAMAICAN RICE AND PEAS RECIPE
INGREDIENTS:
Serves: 4-5
1 medium sized can red kidney beans
1 can coconut milk
2 cups of rice
1 small onion, chopped
1 clove garlic, chopped
1/4 teaspoon dried thyme
1 table spoon oil
1 scotch bonnet pepper (whole, do not chop up)
water
Drain the liquid from the can of beans into a measuring cup and add the can of coconut milk and enough water to make four cups of liquid. Place liquids in a pot with beans, onions, garlic, thyme and oil, bring to a boil. Add rice and stir for a minute. Reduce heat to Medium-Low. Place scotch bonnet pepper on top of liquid and cover tightly for 30 minutes or until rice is cooked. Remove scotch bonnet pepper before serving.
This recipes can also be made using other peas, beans or lentils.
http://www.foodnetwork.com/food/recipes/recipe/0,1977,FOOD_9936_26923,00.html
http://www.foodnetwork.com/food/recipes/recipe/0,,FOOD_9936_18441,00.html