Hey there
@dorothycheung,
Thank you for your wonderful suggestion! We would love to re-add these blocks to the mine depot, but unfortunately we are unable to do so at the moment, because the mushrooms are currently used for models and therefore can't be used as normal blocks.
We hope that this isn't too disappointing to hear and that you will continue to use these forums for any suggestions, ideas or feedback you may have in the future.
Take care and enjoy your day!