As a vegetarian it can be difficult to find much to take to festivals that constitutes an actual meal. I sometimes break for a week and eat fish as that greatly extends my options but I want to try not to this year.
Tins of fruit are a given, plus snack bars etc... last year I took baked beans to eat cold which was great on day one but then the tins heated, cooled and re-heated inside the tent so many times that they made me ill. And I won't be taking a stove or anything.
So... suggestions?! They have stalls etc of course but I wind up spending like £150 on food if I eat every meal from them.
I did some work for a camping company once - their meal in a bag things were actually quite tasty!
I'd suggest things like cooking falafel and keeping it in an airtight container. Not sure if pasta and rice can be unrefrigerated for a few days.. But that with pesto is good cold. And of course sandwiches and the like.
I travel quite a bit & tend to bring things that don't need refrigerated like cans of tuna (if you give into the fish). I always have peanut butter & honey (unless you're vegan) with bread & a bag of pretzel sticks to dip in it too. Along with protein bars & canned meals. And I find corn chips to be pretty filling. Not much fancy when I'm on the road.
I know how hard it can be, I was a vegetarian for about 8 years. Would have been vegan if cheese didn't exist, never desired to give that up. I still think eating meat is way too overrated.
I'm not sure about your side but over here we have a thing where they sell pre-made yeast dough in the supermarkets, we pinch off little balls and deep fry em, they can be kept for about a week and go well with any sauce or jam or syrup. Kind of like doughnuts, but we call it vetkoek. Convenient for fests.
I also love the baked beans tin thing, can't the cans be kept in a cooler?