I've found much of the same material and through research and posts like this one, I believe lairmo is correct. Slag. In my experience there should be more located nearby. Has there been a furnace or railroad located nearby in the past?
We found it on what is now a sports playing field. There is a rail road track about a mile away. We did detect and dig up lots of other rusty nails, screws and some larger pieces of metal that were pretty easy to identify as junk iron. Well I hate to break the bad news to the boys but they were leaning to a meteorite.
Ive found many of those.. Dont tell them till they are older lol. I had a picture my Art teacher drew and I told my mom I drew it she hung it in the living room must have been 15 years later I told her I didn't draw it lol she said yep I knew it all along lol