This is a common question and it is often based on a fundamental misunderstanding. The truth is – There are no special foodstuffs. There is no assortment of foods are the key to your weight gain/loss or otherwise achieving your goals. You can’t go to the grocery store and load up on X and have that be the miracle that gets you over your hurdles. That meal plan the Instagram bodybuilder or personal trainer at your gym wants to sell you doesn’t have anything secret or special in it.
As long as you aren’t eating like an asshole, specific foods will have no noticeable impact, so don’t buy into fads about “superfoods” and other such nonsense. Tailor your calorie and macronutrient consumption to your goals. Within reason, eat foods that you like. If you need more of a specific macronutrient, eat more of any foods that have a higher density of it. If you don’t know of foods that meet specific criteria, just use Google – because answering questions like that is something Google excels at.
For good guidelines on generally improving your diet, have a look at – General Diet Improvement.