"One more mouth to feed" means there is another person that needs to eat. This is a common idiom. Examples: I invited John and Jane to the party so we might have two more mouths to feed. We had one more mouth to feed because Jane brought her teenage son. "We should have more of our own corn now” means that the speaker wants to keep more of the corn that they've grown than has been left for them. This is not an idiom; I've never heard it before.

1, There is one more mouth to feed. = there is one more person to feed/who needs to eat. 2. We should have more of our own corn now . = divide the food more equally. We want a bigger share/ we deserve/ we should have a bigger part/proportion of the food we grew/we cultivated. It is ours; we grew it, and we deserve a bigger amount of it.

1 - "One more mouth to feed" This is a common phrase that often means the family is expecting a baby. 2 - "We should keep more of our own crop." Tenant farmers often lived in poverty due to high rents paid to the landowners. The farmers want to keep more of the crop (they want to pay less of the crop as rent to the landowner).

"One more mouth to feed" is a common phrase meaning that a new baby has been born or is about to be born, (Though it can be used whenever a new person joins a group). So the man is saying they should get more corn, brcause they have more prople to feed.

"There will be one more mouth to feed" = there is a baby on the way, very often. Juan DIego wants to keep a bigger share of what he has grown as his family is about to welcome another child and will need more food.