I am a vegetarian (though I eat eggs). I feel that there are very less items which really help in gaining weight.
As far I know, bananas, bread, sprouts, milk are the some of the items that I have particularly included in my diet to increase weight.
I want to know other items that I could include in my diet. It would be really helpful if someone could provide me the list of options that are available.
I am assuming by weight gain, you mean increase lean muscle mass?
You asked for other items on your list.
I noticed you don't have legumes (aka beans) on your list. I eat lots of beans, particularly garbanzo beans. It is not the most calorie dense food for weight gain (hence why I eat them in large quantities), but beans are super healthy and a great source of protein.
As AutomatedChaos said, nuts (and seeds) are great. Very nutrient dense - high fat, but it's not saturated or trans fats. I like to snack on nuts and/or shelled sunflower seeds, and raisins at work.
Dried fruits (like raisins). Very high in sugars. (make sure it's no "added" sugar. You want the natural sugars in the fruit. You don't want the refined sugar that gets added to some dried fruits.)
Avocados. High in protein. I love them. Eat them. Breath them.
Cottage cheese. High in protein. I get the lowfat kind because it has a higher protein to fat ratio and (to me) it tastes almost as good as the "full" fat kind. The fat free cottage cheese has the consistency of boogers. Gross. If you can stomach it, good for you - it has more protein per gram.
Greek yogurt. First they gave us Archimedes, and now they give us a high protein, pro-biotic snack. Bless them. I like the fat free, NO SUGAR ADDED PLAIN yogurt. The sweetened greek yogurts have a ton of refined sugars in them. Not that healthy.
Supplements. If you're really serious about weight gain supplement your diet with protein powders. Emphasis on supplement. While some products are sold as "meal replacements" you should still eat "normal" food, and supplement a protein shake/smoothie in between meals.
And the list goes on...
On another note, eat healthy, but increase calorie intake dramatically. I find it very hard to gain weight - for example, I must eat continually, all day, high calorie foods to gain but a few pounds. Don't ever let yourself be hungry - always have a healthy snack within reach.
I should also note that I weight train regularly. You don't want to combine a high calorie diet with a sedentary lifestyle unless you want to get really round :)
