xCss. you're at a college man! there's a club/organization for just about EVERYthing that might interest someone. Go join one and you'll find yourself with lots of like-minded people. that'll help you start getting over what is really at its core shyness and insecurity. You're in a strange environment, outside of your comfort level, and you're withdrawing into somewhat of a shell. Totally normal, and it takes effort to come out.
You say one guy at your table has a PhD -- - maybe that indicates you're eating with a bunch of upperclassmen who've known each other for 3+ years - - it can be kinda hard to break into a group like that.
College can be a tough experience, especially if you happen to be mature, because most of the people around you are not (this is why couches get thrown off the roofs of dorms from time to time
)
Just relax and you'll find your niche.