Not sure that you can find them in a pure culture form but could you take a tomme rind and culture it? Or take a trip to France with some pitri dishes? Other option could be to talk to fugi fanatics with libraries of fungi such as Paul Stammetts of https://fungi.com or Tradd Cotter of https://mushroommountain.com
Sorry, missed this, River Bottom. Thank you. Yep, I did "borrow" from a wonderful tomme crayeuse rind and it came out pretty nicely, though I had to learn, IIRC, to distinguish mucor from other similarly-colored spp. Ask me how I know that's a good idea.
And I did a similar approach with the rind off of L'Etivaz - man, I love that cheese. I've forgotten so much and given my bent I can complicate so quickly so to get wet, I may just PLA + possibly MVA + Mycodore it, allow a really gnarly growth before tamping down or brushing back, and see what happens.
I've contacted Coquard because their listing of the P. gris is just too tempting. Looking more, yep, this P. biforme seems to be quite a olayer. First things first. Like getting a good knitting, once again,
Thank you, too, for the fungi sources - very appreciative.