Sporadically mildly toxic?!?! That is Awe. Some.
It would almost be worth trying a taste just to see if you end up sporadically mildly poisoned.
Almost.
But it's a mushroom that tastes like chicken!
Actually, a good number of edible wild mushrooms are inconsistent like this, probable a third of any mushroom books will have these warnings ("Edible With Caution"). It's not unusual for some people to get a reaction while others do not, for toxin concentrations to be normally low but occasionally higher, or absorb toxins from their environment, such as from their host plant. According to wikipedia, with this particular mushroom compounds from a host eucalyptus can accumulate and cause nausaea or headaches. Typically when something is considered "edible" they are normally not toxic, but occasionally mild, non-life threatening symptoms can occur in some situations. Many boletes for example have a slime coating which must be removed, else they will cause you to feel a bit ill.
Aside from a few, I don't know of any such which would typically cause you to actually get "sick" aside from some passing gastrointestinal problems, though in some people it can be a more severe. There are a few which people say things like "ok if you boil three times and discard the water, otherwise you'll die" - but personally, I hardly think any mushroom is worth that much trouble/risk.
In any case, it is never recommended to feed small children any wild mushroom, at least not in a culinary - as opposed to a survival - setting. There are a few where the entire genus is not toxic and it's easily identified, puffballs and certain shaggy inkys and jellies (tree ears, etc), that I wouldn't feel too bad giving my kids, but just to be safe I don't.