This is from the first grow I did, PF tek style but with a few updates. I did a couple monotub grows a year later that went great but I can't for the life of me find any pics.
The white pebbles are perlite and the cake is mostly rice bran meal and fine vermiculite, with a little coffee and gypsum.
in addition to everything else, unclebens on reddit has a lot of beginner resources; using bags of precooked rice is easier in principle than sterilizing your own mushroom food