var fields = GetType().GetFields(BindingFlags.Instance | BindingFlags.NonPublic);
List<Button> buttons = new List<Button>();

foreach (var field in fields)
{
    if (field.GetCustomAttribute<SerializeField>() != null && field.GetReturnType() == typeof(Button))
    {
        buttons.Add(field.Name, field.GetValue(this) as Button);
    }
}