some mushrooms as well. your problem will be in getting a balance. cereals also contain protein, but it is hard to get all the essential amino acids without using pulses (beans and peas). Try some of the commercial things- Quorn or TVP. or even tofu if you like it. Otherwise you are in danger of malnutrition.
Cook those mushroom with beansprouts for the perfect protein.
Rich, real,whole grain wheat bread and believe it or not potatoes have some protein.
Have you tried tempeh? [must cook it] they have several types, not just those made with soybeans. If you slice it and fry it with garlic until crispy, you are getting a perfect protein and other nutrients that grow with the culture.
And man it's delicious.