Matki, Mat Beans, Turkish Gram, and Dew Bean are other names for them. Turkish/Dew gram is a protein-rich, drought-resistant legume that is popular in India.
They are tiny, brown lentils with a yellow interior that are used in a variety of recipes. They sprout beautifully, and I frequently use them in curries like this one with sprouts or the well-known Misal Pav from Maharashtra.