Is there a way to insert an image inside a cell?
When I choose "Insert -> Picture" it inserts it so it's floating over the cells. That's not what I want.
I want to be able to insert the image into cell A1, for instance.
Cannot be done. Cells are for alphanumeric data only.
Anything else, like an image, would only be pinned to the cell, but not inserted.
You can try and fudge it by resizing or merging adjacent cells to fit around the image thereby making it look like it's inside.
But no, you can't insert an image into a cell.
Adding on to @Dean's answer, the "Send to Background" option is under the "Arrange" submenu in the image's context menu (i.e. right-click menu).
After you do it, the behaviour depends on how it's anchored.
The image seems to be anchored not just by its top-left corner, but also by its bottom-right corner. If the bottom-right corner is inside the same cell as the top-left corner, making the cell bigger won't affect the image's size. But if it's inside another cell, then it will.
Most "interestingly", if you make the cell smaller, then the image overhangs the next cell, and the bottom-right corner anchor finds a new home in it! Henceforth, it will behave as the image on the right: resizing with its home cell's size.
I can only assume that this insane functionality is there to mimic what happens in Excel, which, in turn, must have been a well-meant initiative by someone at Microsoft mutilated by some internal deadline or the victim of a bumpkin focus group, and forever preserved in this form by the doctrine of backward-compatibility.
A procedure for working around the beauty:
Now the image will resize with the cell, and act as the cell's background in general. Voila! You can type into the cell, etc. To get rid of the image now, you will have to select the four cells (the main one and its neighbours to the right and bottom), and "Delete Contents" from its right-click menu.
send to background once the picture is properly aligned, its a way around locking it.
Insert image in the normal way, then right click, Anchor > To cell.
There you have it. I don't understand why is it necessary to put in background, it's just working fast and fine.