Its actually hard to be deficient in protien as its in most foods including fruit and veg and starchy foods like rice, bread and potatos, so you dont actually need to eat that much more to stay healthy. Most people eat too much protien which can cause kidney damage amongst other things.
I dont eat many nuts apart from brazil nuts. Other sources are beans (including baked beans, kidney beans, haricot beans, chickpeas, lentils and just about any bean that you can think of). Soya products like tofu, soya cheese, milk and yoghurts (which are also a good source of calcium especially if they are fortified), yeast pates, and most meat alternatives that you can buy.
If you still eat dairy and eggs there is of course eggs, milk, cheese, yoghurt and quorn products (dont know if they have that in the US), but its for sale in basically every UK supermarket. Like meat, these are all pretty high in saturated fat though (apart from maybe quorn which is made from fungi, but uses egg as a binder).