Just like I've said before, I think there are often many meanings for things in the Bible, especially when we are dealing with objects that are often used as symbolic such as bread, wine, and fish. If we think about 'bread' and it's many implications in the Bible we should look at some of the scriptures where it is used. For example:
John 6:35 “And Jesus said unto them, I am the bread of life: he that cometh to me shall never hunger; and he that believeth on me shall never thirst.”
Matthew 4:4 But He answered and said, "It is written, 'MAN SHALL NOT LIVE ON BREAD ALONE, BUT ON EVERY WORD THAT PROCEEDS OUT OF THE MOUTH OF GOD.'"
John 6:51 I am the living bread that came down from heaven. If anyone eats of this bread, he will live forever. This bread is my flesh, which I will give for the life of the world."
And, there are a lot more verses that refer to bread in the scriptures. There was the show bread or the Bread of the Presence in the Temple, the unleavened bread to be eaten at passover, and so on. However, I think the verses that Neil refers to that have to do with not wasting the left over bread have to do with Jesus Himself. Jesus will give us an overabundance of what we need:
Psalm 23:5 Thou preparest a table before me in the presence of mine enemies: thou anointest my head with oil; my cup runneth over.
Even though he provides us with more than we need we should not waste it among those who will ridicule us:
Matthew 7:6 Give not that which is holy unto the dogs, neither cast ye your pearls before swine, lest they trample them under their feet, and turn again and rend you.