There are so many types of noun clauses: wh-clauses, that-clauses, etc.
In most cases, when they are subjects, they are followed by a verb in the singular form.
But are plural verbs used when they are implying multiple things?
Where I went is/are China, Japan and Korea.
What I look for is/are books, shoes and vegetables.
Where I went includes/include China, Japan and Korea.
When I want to go to work is/are Monday, Wednesday and Friday.