|Flint and a chuck of quartz-something|
Anytime you go to the bank, hospital, college, botanical garden or city park, always be on the lookout for decorative rock beds or landscaping that incorporates rocks. Attractive river rocks are often trucked in from other places. If rounded limestone or quartzite are present, you might get lucky. I found thousands of enormous, dagger-worthy nodules among other rocks outside a doctor's office.
The easiest way to identify flint is to strike it, and then smell it. If you roll the wheel on a cigarette lighter, that's the smell. Do you get edges when you break it? If you strike it in the dark, you'll get a few sparks. The outside should be 'nodular' and semi-smooth for flint.
Often railroad tracks and highways are ballasted with some variation of limestone and quartzite. Technically speaking, depending on one's interpretation, this would more likely be chert, although is basically the same thing since no one definition separates the two.
If I can get past amateur hour, maybe I'll have some stone arrows worth posting.