“Mushroom material” is not a complete product description. Spawn is inoculum used to introduce the chosen fungus. Prepared substrate still needs the next operations for its method. A colonised bag has already undergone growth, but may still need maturation or other preparation before fruiting.
Ask the supplier to state the species, strain where relevant, batch identity, preparation or inoculation date, stage at dispatch, transport conditions, storage instructions and work remaining after receipt. Keep those answers with the order.
On arrival, compare the actual label and package with that agreement. Record receipt time, package integrity and any discrepancy before mixing lots or allocating material. Quarantine unresolved supplies under a suitable procedure and ask for clarification; a healthy-looking photograph is not a purity test.