For get display name value you should use System.Reflection. And then you could do this in simple way:

   public enum TCountryNames
    {
        [Display(Name = "America")]
        cnUSA = 1,
        [Display(Name = "England")]
        cnUK,
        [Display(Name = "CHINA")]
        cnCHN
    }

public class EnumData
{
    public int Id { get; set; }
    public string? Name { get; set; }
}

public class MyClass
{
    public static List<EnumData> GetEnumList()
    {
        var list = new List<EnumData>();
        foreach (var e in Enum.GetValues(typeof(TCountryNames)))
        {
            list.Add(new EnumData
            { 
                Id = (int)e, 
                Name = e.GetType()
                    .GetMember(e.ToString())
                    .First()?
                    .GetCustomAttribute<DisplayAttribute>()?
                    .GetName()
            });
        }
        return list;
    }
}

So to clarify:

• you create loop foreach enum
• take id by casting
• take name using reflaction - I added all needed protection against null exception

Output: [ { "Id": 1, "Name": "America" }, { "Id": 2, "Name": "England" }, { "Id": 3, "Name": "CHINA" } ]

For get display name value you should use System.Reflection. And then you could do this in simple way:

   public enum TCountryNames
    {
        [Display(Name = "America")]
        cnUSA = 1,
        [Display(Name = "England")]
        cnUK,
        [Display(Name = "CHINA")]
        cnCHN
    }

public class EnumData
{
    public int Id { get; set; }
    public string? Name { get; set; }
}

public class MyClass
{
    public static List<EnumData> GetEnumList()
    {
        var list = new List<EnumData>();
        foreach (var e in Enum.GetValues(typeof(TCountryNames)))
        {
            list.Add(new EnumData
            { 
                Id = (int)e, 
                Name = e.GetType()
                    .GetMember(e.ToString())
                    .First()?
                    .GetCustomAttribute<DisplayAttribute>()?
                    .GetName()
            });
        }
        return list;
    }
}

So to clarify:

• you create loop foreach enum
• take id by casting
• take name using reflaction - I added all needed protection against null exception

Output: [ { "Id": 1, "Name": "America" }, { "Id": 2, "Name": "England" }, { "Id": 3, "Name": "CHINA" } ]

Example: https://dotnetfiddle.net/XVL2LI

For get display name value you should use System.Reflection. And then you could do this in simple way:

   public enum TCountryNames
    {
        [Display(Name = "America")]
        cnUSA = 1,
        [Display(Name = "England")]
        cnUK,
        [Display(Name = "CHINA")]
        cnCHN
    }

public class EnumData
{
    public int Id { get; set; }
    public string? Name { get; set; }
}

public class MyClass
{
    public static List<EnumData> GetEnumList()
    {
        var list = new List<EnumData>();
        foreach (var e in Enum.GetValues(typeof(TCountryNames)))
        {
            list.Add(new EnumData
            { 
                Id = (int)e, 
                Name = e.GetType()
                    .GetMember(e.ToString())
                    .First()?
                    .GetCustomAttribute<DisplayAttribute>()?
                    .GetName()
            });
        }
        return list;
    }
}

So to clarify:

• you create loop foreach enum
• take id by casting
• take name using reflaction - I added all needed protection against null exception

For get display name value you should use System.Reflection. And then you could do this in simple way:

   public enum TCountryNames
    {
        [Display(Name = "America")]
        cnUSA = 1,
        [Display(Name = "England")]
        cnUK,
        [Display(Name = "CHINA")]
        cnCHN
    }

public class EnumData
{
    public int Id { get; set; }
    public string? Name { get; set; }
}

public class MyClass
{
    public static List<EnumData> GetEnumList()
    {
        var list = new List<EnumData>();
        foreach (var e in Enum.GetValues(typeof(TCountryNames)))
        {
            list.Add(new EnumData
            { 
                Id = (int)e, 
                Name = e.GetType()
                    .GetMember(e.ToString())
                    .First()?
                    .GetCustomAttribute<DisplayAttribute>()?
                    .GetName()
            });
        }
        return list;
    }
}

So to clarify:

• you create loop foreach enum
• take id by casting
• take name using reflaction - I added all needed protection against null exception

Output: [ { "Id": 1, "Name": "America" }, { "Id": 2, "Name": "England" }, { "Id": 3, "Name": "CHINA" } ]