Pen Blanks from the Urban Jungle
Walk into Woodcraft store and have a look at the prices for pen blanks.  Pen blanks are not cheap and depending on the type of wood, you can pay $10.00 or more for one blank.  

In my experience  making a pen out of a really special and expensive kind of wood most times does not mean that much to the person you made it for -  other  than the fact that you made it,  it is made out of wood  and the wood has a nice pattern.

So, if that is the general rule, why pay the big $$ for pen blanks when something from the urban jungle would do just as well.

One reason is because these types of woods generally don't have much in the way of pattern or color.  That is a pretty good reason.

Another reason is this kind of wood is usually green.  Green wood shrinks, splits and if you are looking to make a pen tomorrow,  you might be out of luck.  That is another pretty good reason.

There is a solution.

 
The first thing to do is locate some wood which has a thick sapwood layer   - around an inch or so, about the approximate diameter of a pen blank. This is not absolutely necessary but if you wish to make a pen out of cross-cut wood and want matching pieces, it should be close.  We are interested in this to get a good color variation.

There are lots of places to obtain green wood: 

A call to your local arborist

The Dump

The Dump

Downed Trees

Tree Cutting after storms

Limbs

Find out when utility companies are trimming trees - they usually have an easement.

Your own back yard

Fire wood suppliers

Utilities were clearing branches from power lines and this chunk came from refuse pile.
It is about the right size and has a nice, thick sapwood layer. The interior is quite dark, which should make a nice contrast
.
Cross-Cut Blanks
The first order of business is to cut a chunk roughly the length of a pen blank.  Always leave it a little long because the blanks will shrink when dried.
For Cross-cut pieces, try to avoid the innermost rings. The further you stay away from them, the less likely the blanks are to split in half.  
The first order of business is be safe and cut a flat spot. This will keep the wood from turning if you are using a band saw.  
Cut the pieces a bit thicker than a dry pen blank
Outline the blanks using a good, thick pencil or pen.  Try to stay away from the center.
Cut the outermost edges first.  The reason for this is to draw the blank as far away from center as possible when making the inside cuts.
Set up the band saw to cut an 1/8" or so wider than the usual pen blank to account for shrinkage.
Make the interior cuts.
Square the rounds.  Have a look at both all sides of the blank and determine which sides will give you the most white and then trim the opposite sides.
I generally mark matching pieces with something heavy like a grease pencil if I want a matching pen and pencil set.
Square off the ends and set aside.
With the Grain
Figure out which position will give you the most white and then cut a flat spot.
Make a series of cuts which gives you about half white and half dark.  A piece this size will require about four cuts.
The pieces in front and on the left will be used for blanks.  The upper right piece is the center of the branch and is discarded.
Use a pen blank as a guide to figure out where to cut and produce a full sized blank.
In an ideal world, the center should be half white and half dark.  Bear in mind the diameter is going to be considerably reduced when turning a pen. Too much of one color or the other and you can end up with a mono colored pen.
These are cut to size. Some of these may be discarded but who cares, it's free wood anyway.
45 Degree Cut
45 degree cuts produce some interesting effects.  Try turning one of these before a 90% cut.  It gives you a flavor of turning against the grain.  
It is difficult getting an entire blank from 45 degree cuts.  Keep the short ones and match them up for more interesting effects.  You waste  a lot of wood doing these cuts but it's free anyway.
Drying
There are many methods for drying green wood.

I prefer the microwave method.

Word of warning:

Unless you have a very understanding significant other or a microwave out in the garage,  it is best to do this when the spouse is out of the house.

I take about 20 blanks at a time and microwave them on Defrost (strong emphasis on the word Defrost) using a 2 lb setting, or for about 14 minutes.

Keep an eye on the blanks.  Catching them on fire is not a good thing.
Remove the blanks when time is up and lay out so all sides are exposed.  Let them cool for half an hour or so.

Wipe out any accumulated water in the microwave tray.

One of the drawbacks to using a microwave is microwaves are supposed to keep moisture in, not out.


Repeat the process two more times.

Note: All microwaves are different so test times and settings carefully, erring on the side of caution.

After nuking the blanks three times, I set them aside for a week or so and then determine whether or not they need to be nuked again.

Some people use a gram scale when in a rush.  They nuke the blanks until there
is no difference in the last two weight measurements. 

Two blanks can easily be dried in a couple hours.  Two blanks work out to about 30 seconds on the defrost setting using .5 pound defrost weight.  

I think it is best to wait for at least a few days to let the blanks stabilize out with the environment.

Four Days Later - A bit about Cross-Cut Blanks
Here are a couple cross-cut blanks.  
Rule #1 is ensure your tools are really sharp.
Rule #2 is prepare a couple extra blanks as spares.  It is very easy to tear one of these up when getting close to the finish line.
Trimming the edges on the band saw before starting is quite helpful.
I have found setting the guide normally when turning cross-cut blanks is not the best idea.
This is what typically seems to happen with a normal guide setting.  What I do is raise the guide to where you are more skimming off the top and angling down a bit with the tool - kind of like you would when using a skew chisel.  

The other reason for seeing this is using a dull tool.
Raising the guide really helps.  No disasters yet.  
Time to sharpen the tool again as  preventative measure against a blank flying apart.
I always use a sanding block when dealing with woods of unequal density.
The sap wood (white) will sand down faster than the heart wood.  
A sanding block helps equalize the pressure.
Oak
And here are the results

Set1:

Top Pen Blank - With the Grain
Middle Blank -  45 Degree Cut.

Bottom Blank - Cross  Cut

Last Pen:

This comes from a couple chunks of wood I found with the other ones.  The bark was silvery gray and the wood itself was more white than anything.  I started cutting it up and was rather surprised to find this kind of semi-spalted patterning.... and I have about ten pounds of the stuff.  White Oak?

All are sanded to 400 Grit and then finish sanded with EEE.

Polish: Mylands High Build Friction Polish