In the Old Country of Switzerland they are called a "Wetzstein". You should be able to google some images. It is a whet stone used for sharpening grain sickle etc. Hope this helps. Buster
Nice finds. Im would agree with logueb on the stone. Early sickle sharpener. I have found a couple stone tools on indian sites that were similar in size and shape but they had no signs of any wear from sharpening and were probably used for other purposes.