Powershell find and store the file name

Some options for your specific use case

Get-Item myf* | Select-Object -ExpandProperty Name
(Get-Item myf* | Select-Object Name).Name

A bit of backgroud

The Select-Object Name still returns an object, not just a string.
You can verify yourself by adding | Get-Member

   TypeName: Selected.System.IO.DirectoryInfo

Name        MemberType   Definition                    
----        ----------   ----------                    
Equals      Method       bool Equals(System.Object obj)
GetHashCode Method       int GetHashCode()             
GetType     Method       type GetType()                
ToString    Method       string ToString()             
Name        NoteProperty string Name=myfile