Can you store multiple MySQL indexes in one cell and retrieve them via JOIN?

I have a MySQL table called "Box." Each entry has a number, a label, and content.

So

ID – NO – LABEL – CONTENT

The CONTENT column should summarize the content. For this purpose, there is a second table called "Contents." It would look something like this:

1 – Bread
2 – Milk
3 – Sugar
4 – Apples

I want to use the indexes from the second table in the CONTENT cell, but multiple times. For example, one of the entries in the CONTENT cell would be "1,2,4" if it contained bread, sugar, and apples.

Is it possible with MySQL and, for example, a JOIN to separate these indexes in the cell and then retrieve them individually from the second table?