Text inside shape in Eagle
This is called 'negative', or 'inverted' silkscreen. You can't do it directly with Eagle as there is no built in function.

However the is a ULP available from the Cadsoft website here called negasilk. It's not very clear initially how to use it, but after a bit of testing you basically do the following:


Open a new .brd file and save it as something.
Draw a polygon on the Layer 1 (Top) which is the size and shape of the area you want to be your 'Background'. According to the ULP comments this should be set to have a width of 8 mil, and an isolate of 0 mil.
Next, draw on Layer 41 (tRestrict) whatever you want to be cut out. You can use the text tool if you want, just make sure to set it to have a Font of Vector.
Once done click the Ratsnest button to fill in the copper area, you should notice that the polygon is cut out around the stuff you put on the tRestrict layer.
Save the board as something, and then run the negasilk.ulp file.
The ULP should create a script with the same name as the board in the same folder as the board. This is a script to generate the silk.
Open a new library (or an existing one, up to you)
Open a package in the library (or create a new one)
Run the .scr file that was created by negasilk. You should whatever shape the copper was gets drawn out on the silk layer in the package.
Save the library.
Finally in your actual board design, go to Add Package and then select the package you just created in the library. This doesn't need to be done in the schematic as there is no symbol or device associated with the package.




It's a bit long winded, but it is probably the best you are going to get short of drawing it out yourself. If you want to change the silk, repeat the steps.