Yes, there is a possibility to convert those starches into fermentable sugar, but it will depend on the source.
With malt, the process of mashing consists in keeping the grain at a temperature to activate enzymes that will perform the starch conversion. Those enzymes are present in base malt (we call that the "diastatic power" of the malt). But those enzymes may or may not exist in your "source", so you will need to add some malt or enzymes to have a conversion of starches.
You may find Diastatic Malt Powder for sale, or buy some base malt to mix with your other "source" during mashing.
As for the yeast, any beer yeast will work (even wine yeast) but they each have their own characteristics.