straw

• dry threshed grain stalks (used for bedding, animal fodder, basket weaving, etc.); single stalk of grain; hollow slender tube used to suck up liquids; something of little importance
of or pertaining to straw, made from dried threshed grain stalks; containing straw; pale yellow, straw-like in color; worthless, unimportant
straw is the dried, yellowish stalks from crops such as wheat or barley.
a straw is a thin tube of paper or plastic, which you drink through.
if you are clutching at straws, you are trying unusual or desperate methods to achieve something, often because other methods have failed.
if something is the last straw, it is the latest in a series of bad events, and makes you feel that you cannot bear any more.