For sale here is a 2-pack of spore swabs. The spores are from a Salem, OR collection of elm oysters (Hypsizygus ulmarius).
These mushrooms typically grow in clusters of 1 to 3 specimens. They are not a "true" oyster (Pleurotus) but rather an oyster-like mushroom. They grow on fallen maple branches here in the Willamette Valley and they are delicious.