SQL query syntax for enums

I am using C# and I have a column defined in a table using an enum like so:

[Type]
public enum Topping
{
    Cheese,
    Ham,
    Mushroom,
}

[Table(Name = "pizza", Public = true)]
public partial class Pizza
{
    [AutoInc]
    [PrimaryKey]
    public int Id;
    public Topping Topping;
}

When I query "SELECT * from pizza" I get a result like:

 Id   | Topping        
------+----------------
 2248 | (Cheese = ())  
 2249 | (Ham = ())     
 2250 | (Ham = ())     

But what is the syntax for querying based on the Topping column e.g. "SELECT * from pizza WHERE Topping = Ham"?
I couldn't find any info in the docs about this. It would be a welcome addition to add some examples of queries with WHERE clauses on other data types e.g. enums and structs.

Start from the C# enum and Pizza table definition shown in the issue, then verify the syntax for filtering enum columns in a SELECT WHERE clause. Document the working query and, if supported, add examples covering enum and struct values; done means a newcomer can find and use these examples.