What are the metamers of penta-1,2-diene?
Yes. Consider metamer to be a different word for isomer, as noted by Lighthart:


  The term metamer is equivalent to isomer...As an aside, I have never heard the term metamer before, I expect it is archaic.


And, according to Dictionary.com, consider a diene to be:


  a hydrocarbon that contains two carbon-to-carbon double bonds in its molecules.


There are too many diene isomers to be listed here ($\ce{C5H8}$ has many atoms), but you can begin by changing the numbers in the name to generate different Lewis structures.

Penta-1,2-diene:



Penta-1,4-diene:



This is just one structure. Try cis vs. trans, position isomers, etc. You may think of many more.