ID Help (See other sample pics Of largest)

I have found a few of these now and am beginning to wonder if they are partial teeth. The first one, I thought was possibly bone or a tooth (definitely not a rock) then I found a couple more with the same basic shape and markings and started to think they may actually be teeth? I don't think pictures tell the story very well (not with this little point and shoot anyway) so I may need to hand these to someone in the know for a proper ID. I just thought I'd post them anyway to see if recognizes anything.