I was walking in a cornfield this afternoon. It is located in the Midwestern United States. I found this particularly interesting piece of flint. It has a sharp edge all the way around. I don't think it is an arrow or spear head. However, I find it hard to believe that this piece of flint would be sharp all the way around. Perhaps it was a small axe head?
I agree with @Jimmy Fix-it, it doesn't appear to be naturally shaped.
I am certainly no expert on stone tools and it is a little hard to see from your images, but it looks a little like it has been knapped for shape and and looks like it has been pecked along the edges at least partially. It may be that it is an unfinished tool as it appears only partially worked, but scrapers and hand choppers often appear unfinished. As you know where it was found, some things to consider about the object - are there other stones around that are similar? Is the type of stone one that is commonly/naturally found in your area?
Your best bet for identification is to take it along to your local museum and ask them about it.