Can I ask professor to send me a copy of papers? I'm a senior in college and working for my final year project. I am required to read more than 8 papers. However, 2 of them cannot be found online or in the library (Summon system). The library delivery service is inaccessible now, and I believe my advisor have that papers.

Can I ask professor to send me a copy of the papers? Is it impolite to ask such favor or illegal?
Yes, you can, and you should. It is not impolite (unless you actually have access), and it is not unethical. I don't think it is illegal, if you do not distribute it further, and it is certainly not uncommon.

First, make sure you really don't have access (otherwise, you risk looking a bit like a fool), then ask him. Don't make a big deal of it, just explain that you lack access and you believe he may have them, if so could he please send them.