[c#] Shortcut for creating single item list in C#

For a single item enumerable in java it would be Collections.singleton("string");

In c# this is going to be more efficient than a new List:

public class SingleEnumerator<T> : IEnumerable<T>
{
    private readonly T m_Value;

    public SingleEnumerator(T value)
    {
        m_Value = value;
    }

    public IEnumerator<T> GetEnumerator()
    {
        yield return m_Value;
    }

    IEnumerator IEnumerable.GetEnumerator()
    {
        yield return m_Value;
    }
}

but is there a simpler way using the framework?