give us this day our daily bread ...

once upon a time, not too long ago, the good people of britain used to divide up their bread according to status.
workers/servants got the burned bottom bit.
family members got the middle bit.
and guests got the top... which naturally led to that well known expression, the upper crust.

doris baked a loaf today. 
she gave me a slice.
then ate the rest herself, with a round of cheese and a field of tomatoes.

hence that other well known expression - greedy pig.