Lupe,
Your best best for Agarita limb pieces is to cut them into 1/2 blank sizes or just long enough to make each barrel of a pen. Label corresponding pieces so you can get a good grain match. Now put them in your vise and drill the very center with a bit a couple sizes smaller than you will need for the kit. Then air dry as normal and most will not crack. By drilling the center you are removing the pitch and leaving room for the wood to shrink into itself rather than crack. At least I have had good luck with this method but your mileage my vary.
I no longer use the branches since they are pretty boring other than having a nice color. If you want something spectacular, dig up the root and dry it in your toaster oven. Then dig out all the rocks, dirt, etc. and cast it in resin using my "Worthless Wood" process. The roots is where all the best grain is.
BTW, when are you going to come by for a visit? You are so close, you might as well make a trip over here some weekend and I will show you how I deal with Agarita!