The first thing that happened on their journey was the mixed multitude that had joined them from Egypt began to murmur about the food. As you may recall, that was just manna for breakfast, lunch, and dinner. They didn't have any onions and garlic to season it with. This caused the mixed multitude in Numbers 11:4b-15 to want some Egyptian food, and this stirred up the lust among God’s people. Witness Lee says that this lust was already hidden within them, but the environment brought it out.
And the mixed multitude that was among them lusted exceedingly; and the children of Israel also wept again and said, Who shall give us meat to eat? We remember the fish which we used to eat in Egypt for nothing, the cucumbers and the melons and the leeks and the onions and the garlic; But now our appetite has gone; there is nothing at all but this manna to look at. Numbers 11:4-5
God wasn't too happy with all these complaints. He sent quails to their camp for 30 days that were about 3 feet high and a day's journey on each side. As they were biting into it, God sent a huge plague.
So what lessons are in this account? I learned from my reading that the foods in Egypt symbolize the worldly taste, and the manna they detested represented Christ as the heavenly bread. We might experience this, too--the world may cool us down, and we may not always want to come to the Lord’s word and eat the spiritual bread. This is brought out on pages 130-131 of chapter 18:
Manna signifies the heavenly Christ as the daily food for God's people. This is pointed out by the Lord Jesus Himself in John 6:29-35. In the wilderness the people became bored of eating manna. Day after day, they received the miraculous supply of manna. No matter where they were, there was enough manna in the morning to feed more than two million people. This surely was a miracle. But even though the children of Israel witness this miracle daily for forty years, they were not affected by it in a positive way. Instead they became tired of manna, even bored of eating it....If we are honest, we will admit that just as the children of Israel were bored of eating manna, we have sometimes become bored of eating Christ as our daily food (Lee. Witness. Living Stream Ministry: Anaheim. 1990, Print).
What's helped me not get bored is to come to God's word with a seeking heart and ask Him to give me a word. We can ask the Lord to never let us get bored of coming to the Bible. I can honestly say He can do that.