A thing to note on mushroom garden is that it has a completely separate counter. one that does not reset when changing gardens.Revision 237 adds support for Your Mushroom Garden.
Along with all the other garden crops, you can include one of the following crops for that garden:
plump free-range mushroom
bulky free-range mushroom
giant free-range mushroom
immense free-range mushroom
colossal free-range mushroom
If you have the appropriate mushroom in your garden, it will fight through piranha plans (using "garden pick") and pick it.
If you have a lesser mushroom in your garden, it will fight through piranha plants (using "garden fertilize") and fertilize it.
The built-in "garden" command does all the work: pre-fight restoration, combat using your chosen battle action (or CCS), between battle script, and so on.
It works like a charm if you've been visiting Your Mushroom Garden via KoLmafia and therefore know the actual state of your garden.
If not, you may be farther along than KoLmafia knows. I suppose I could reproduce that logic and pick if you are actually at the desired goal.
But sans that, KoLmafia will synch up when it sees The Mushy Center, so you'll be good to go tomorrow.