There are some in the genus Lepiota that are listed as poisonous I didn't check all of them, and I can't make an ID for certain for you on that one, there are quite a few that have similar specs and as a newbie to mushrooms I wouldn't feel confident in any ID. I'd pull up all the ones you see and toss them in the trash or compost them. At least with most mushrooms after a short while their flush for the season is over and you won't see them till next year (if they ever do come back). I can understand your concern, I don't have a toddler, but I do have young cat that keeps me on my toes (she likes to chew up and attack mushrooms, and pulls habaneros out of basket if I set it down after picking & carry them all over the house hiding them, and of course she carries them in her mouth!) so I'd play it safe and keep the little one inside till you can do a scan of the yard, and get rid of them if you think your baby might try to sample them.