My shiitake culture should be arriving in a couple of days, so I got a few growing bags made up and ready for pressure cooking. I mixed 1L of maple wood pellets with 1.5L of water and 500mL of used coffee grounds, then put it into two vacuum sealer bags with DIY Tyvek air filters. Adding water to the pellets is amazing. They immediately begin to swell and rise like dough, then crumble into sawdust at a touch. I'm not following any tried and true method here, I'm just going to see how it goes.