Can someone tell me how to get a gnomish perspective hat item?

@dieanothernight Hey, it looks like your post was in the section for the old tower defence PvZ game, so unfortunately it was missed, sorry. 

As for your question, as I understand it you need to find all of the gnomes then go to the secret room. 

This video may help: https://www.youtube.com/watch?v=ilwJ26EuooE

Thanks.