using System;

using System.Linq;

using System.Collections.Generic;

using System.Runtime.Serialization;

​

public class Program

{

    public enum Baah

    {

        [EnumMember(Value = "aa a")] aaa,

        bbb,

        ccc

    };

    public class SomeClass

    {

        public Baah baah;

        public SomeClass(Baah baah)

        {

            this.baah = baah;

        }

    }

    public static void Main()

    {

        List<SomeClass> someClasses = new List<SomeClass>();

        someClasses.Add(new SomeClass(Baah.aaa));

        someClasses.Add(new SomeClass(Baah.ccc));

        object? v;

        SomeClass someClass = someClasses.FirstOrDefault(s => Enum.TryParse(typeof(Baah), "aa a", out v));

        Console.WriteLine("SomeClass: '" + someClass?.baah ?? "none"+ "'.");

    }

}