Here is a general purpose tree traversal implementation that doesn't use recursion:

public static IEnumerable<T> Traverse<T>(T item, Func<T, IEnumerable<T>> childSelector)
{
    var stack = new Stack<T>();
    stack.Push(item);
    while (stack.Any())
    {
        var next = stack.Pop();
        yield return next;
        foreach (var child in childSelector(next))
            stack.Push(child);
    }
}

Use a Queue instead of a Stack for a breath first, rather than depth first, search. Use a PriorityQueue for a best first search.

Here is a general purpose tree traversal implementation that doesn't use recursion:

public static IEnumerable<T> Traverse<T>(T item, Func<T, IEnumerable<T>> childSelector)
{
    var stack = new Stack<T>();
    stack.Push(item);
    while (stack.Any())
    {
        var next = stack.Pop();
        yield return next;
        foreach (var child in childSelector(next))
            stack.Push(child);
    }
}

In your case you can then call it like so:

IEnumerable<Node> allNodes = Traverse(pRoot, node => node.Children);

Use a Queue instead of a Stack for a breath first, rather than depth first, search. Use a PriorityQueue for a best first search.