Well, there's your problem.I have a treat mix with some scratch mixed with sunflower seeds and meal worms - and give about 4 cups (33 hens) a couple times a week. Not a lot for sure.
Your veggies are fine - mostly water, some sulphur vitamins and fiber, not much else. The weeds aren't the problem, either.
Sunflower seeds are (varies) around 44% fat. Yes, they are high protein, but they are 9-12 times the recommended fat content ina chicken's diet. Live mealworms are about 20% protein (that's good) and 13% fat (that's not). Dried, the numbers are more like 55% protein, 30% fat. That fat intake isn't something the birds need - even feeding "extra" fat as a carb replacement to help with heat management, you shouldn't be over 6% fat, maybe 8% with a meaty intended for quick harvesting.
"not a lot for sure".
Actually, the recommend is that treats like you describe above not exceed 10% of a birds diet, by weight, daily. Better to feed less. Thumb rule is that a bird consumes 1/4# feed daily (100g if you prefer). 1/10th of that is .4 oz, or around 10g, which is basically a mostly level tablespoon. There are 16 tablespoons in a cup - so your scratch offering is twice the maximum recommend for 33 birds and honestly, its more calorie (fat, specifically) dense than most feed as scratch (most of us, when we offer scratch, offer the cheap stuff - corn, millet, milo, maybe some sunflower or safflower seed). They will likely love you less (but live longer) if you cut that to not more than 1 cup per day.