A yardstick is a rather old-fashioned measuring instrument that most of us don’t come into contact with.
Its main use in modern times is as an abstract metaphoric measuring tool for comparing things to the standard for excellence in a particular field, object or device. For instance Charles Dickens might be a yardstick for literature, or an iPod might be a yardstick for mp3 players – so all subsequent mp3 players are measured against the iPod, the yardstick for excellence in mp3 players.
Yardsticks are also used for pointing at things sometimes.
Because yardsticks are not seen these days, and are only really a metaphor themselves, it’s quite rare for one to appear in a dream. However if you do dream of a yardstick it will be important to note what context it was used in, who was holding it and/or what it was being used for.
An example might be your friend Steve (or whoever) giving a lecture on saving money, using a yardstick as a pointer. In this case your dream may be suggesting that Steve should be your yardstick for financial matters.
The yardstick is a symbol of sound judgment and right thinking, a way of showing us the accepted standard, and should be treated as such when appearing in your dreams.