As long as your kids aren't at a age that randomly put stuff in there gobs they will be fine, I found the prompt feeding of the odd fresh dandilion cured most babies of this habit.
I cant clearly id what you have there but none are deadly and even if they were just playing on them ie skin contact isn't dangerous at all.
The bottom one is japanese parasol coprinus species. This is completely not toxic.
The black gilled one at the back looks a bit like a weeping widow lacrymaria velutina, it certainly looks like a psathyrella type which unless you are gordon off ray mears wild food are normally quite edible.
The other hairy one is dependant wether it is on hidden tree roots or not, and what colour the gills are.
Both the coprinus and the psthyrellas like animal poo which more hazardous to children.
