Get all fields (following inheritance chain) using Chain<T>(Func<T, T>) extension method.

GetFields.cs

using System;
using System.Reflection;
using System.Collections.Generic;
using System.Linq;

static class Helper {
	public static IEnumerable<T> Chain<T>(this T first, Func<T, T> follow) where T : class {
		for (T item = first; item != null; item = follow(item))
			yield return item;
	}
}

class Test {
	static void Main() {
		Type t = typeof(SomeDerived);
			
		BindingFlags flags =
			BindingFlags.Instance | BindingFlags.DeclaredOnly |
			BindingFlags.Public | BindingFlags.NonPublic;
			
		var fields = t.Chain(type => type.BaseType).SelectMany(type => type.GetFields(flags));
		foreach(FieldInfo fi in fields)
			Console.WriteLine(fi.Name);
	}
}