Thank you for your prompt response.
We have received only I-797 twice but never got I-90. I-797 will expire 2024 August.
-I-90 is the form your mother filed for her green card extension application. The I-797 is the I-90 Receipt Notice.
I tried to call USCIS but only get computer answer and got disconnected when asking for customer service representative. Does it mean that there is no "human" answering questions?
-The extension date on the I-797 is August 2024, so USCIs will not give your mother the green card stamp now. You may call USCIS to make the appointment on July 2024 to get the green card stamp. Here is the information how to speak to a live person at USCUS:
How do I speak to a live person at USCIS?