Watch out for bugs and termites in that first piece.
I would be a lot more worried about nails, screws and anything metal, there no trees that carry more metal than those coming from backyards, particularly the fruit trees, believe me, I know...!
Well, what would I do, it I was thinking is pen blanks, only, I would cut the bigger lengths about 11" to 12" long (2 pen blanks length) and then I would rip the piece/log through its middle (Pith) with the widest part on the bandsaw table.
That would give you a good view of what you have. If straight cut/with the grain is what you are after, rip each half into 21-22mm boards if the wood is dry and about 25mm if the wood is green. Slice the boards into strips matching then same size as the board thickness and then stack them up with a little space in between the blanks and then strap the bundle tight in cross orientation, let them dry for few months under cover and out of the sun (well ventilated location).
If the wood is dry, you can rip the boards to the normal pen blank size you like and then cut the strips in that same size, cut them to length and start making pens.
PS: Is recommended that you don't start to make pens in the same day as you cut the wood/exposed it to air, it may contain some trapped moisture that will need to dry naturally and that takes about couple of weeks in average temps of 15 to 20° Celsius.
With the green wood, appart from cutting them oversized in its diameter, I would give an extra 1/4" at least, on its length...!
If you aren't going to process that wood into blanks for some time, seal/paint the fresh cut ends...!
Good luck,
Cheers
George
