you need to file to TSC, that your state belongs to. see below

Read I-765 instruction on page 9 (downloaded from USCIS forms).
"... if you filed your I-485 adjustment application with a USCIS service center, you must file Form I-765 at the Nebraska Service Center or the Texas Service Center,depending on where you live (see the following addresses)."
I-765 is processed separately. You need to attach a copy of your 485 receipt. They should be able to locate your file from the system.