Things such as spinach, watercress, kale, leafy salad (Not iceburg though, this can be fed if you have no alternative, but only on rare occasions. beardies love dandelions but id be careful where you pick them from, you don't want outside contaminants such as dog urine, weed killer, fertilizer or even other animal feces.
My beardies love broccoli heads, don't know why but they love it. Carrots seem to help there color, brightens them up it seems. making a mix of veg and dusting with vitamins is a good way of getting there vits down them!
But to your original question, yes but try and buy organic!