My low tech oyster grain spawn experiment was a terrible failure.  Within a few days, the bags and jars were full of various smelly molds, so I had to discard the grain onto the compost pile.

I was shocked to see so many "weed fungi" in the grain since I've had such good luck growing oyster mushroom spawn on cardboard with similar lack of sterility.  I concluded there were two flaws in my grain experiment:

• The oyster spawn I started with wasn't chomping at the bit.  I harvested the mushrooms a few days before our pressure canner arrived in the mail, so I had to store the stem butts in the fridge.  And the fridge has been running too cold, so the stem butts got a bit frosty.  The ice didn't kill the spawn, but it did slow the oysters down so that wild molds had a chance to grow on the grain before the less vigorous than usual oyster spawn took over.
• Grain may simply be too rich of a medium for unsterile conditions.  Since damp newspaper isn't very enticing, most weed fungi can't get a toehold.  But cooked grain is delicious for all and sundry, giving the oyster mushrooms a run for their money.

We've started a bit of newspaper spawn with the last few oyster mushroom stem butts of the year.  Assuming the spawn runs (which it should since I've grown oyster mushroom spawn on cardboard before), I'll have to figure out what to expand the cardboard spawn onto.  Cardboard isn't high enough in nutrients to keep expanding spawn on indefinitely, so I may try inoculating some straw for a bit of indoor culture for the winter.  I'll keep you posted.