Are wheat back pennies valuable

As is the case in so much of life, the answer is that it depends.

Certain dates and mintmark combinations are valuable (for example, 1909 S and 1909 S VDB, 1914 D, 1922 Plain, and 1931 S are the key dates, a dozen-or-so others are known as "semi-key"), and in general coins are worth more the better condition they are in ("better condition", by the way, also means "not cleaned" - cleaning a coin is a great way to destroy value).

A 1909 S VDB in Brilliant Uncirculated condition is worth several thousand dollars. A 1957 in circulated condition is worth two or three cents - the value of the copper contained therein. As I said, it depends.