The lettuce/tomato is one thing, but the cheese is definitely worth listing in your log. That's potentially a few hundred calories not being tracked.
Pieced together from some recent grocery receipts...
5 pounds of russet potatoes (about 18 small to medium potatoes) : $5.99
2 loaves of organic 21-grain bread: $6.79
3.5 pounds frozen organic spinach: 7.49
50oz chopped tomatoes: $4.00
3 dozen eggs: $6.99
2 whole roaster chickens (raw): $18.79
1 bunch bananas: $1.39
$51.44 total. I'm a hair over-budget. Whoops. Plenty of ways to shave down the cost, not going organic is the easiest, but these were pulled straight from some of my own shopping trips.
Chicken, eggs, potatoes, bread, vegetables, and some fruit. Everything a growing boy needs.
Roaster chickens are a great buy. About an hour to cook and you've got several meals ready to go. Two breasts, Two legs, Two thighs, and wings. Throw the leftover carcass in water to make stock, then add some vegetables and pluck off any remaining meat bits and you've got a simple soup.
Are the beans like plain black beans or something? Or are they like Campbell's pork 'n' beans? Chicken breasts, especially if you're getting them skinless, may add up quick unless you're getting big bulk packs of frozen chicken breasts (I've seen sacks of 15+ pounds for like 20 bucks). Pre-cooked rotisserie chickens in supermarkets are also hella-cheap (as the kids would say). Just be aware that the skin may have a marinade or sugar-based sauce on it.
And double check those muscle on a budget articles I posted in the other thread.