Plenty of kids, regardless of their gender, tend to like stuffed animals. I'd call them neutral toys really.
And I know a lot of cis dudes that aren't outgoing. By your mom's logic, they're not guys either. As a kid, I was afraid of taking risks and trying new things. I'm still a bit iffy on them, but I've become a bit more outgoing as I've gotten older. It's not a matter of gender, I think, but rather your environment and personality. Some people aren't athletic, jump-off-every-bridge types, while others are. Hell, I'm in a huge weight training class at my school, and the girls in it are more adventurous and keen on taking risks than the guys are. I've not seen any of the dudes try to climb up the side of the building to get to the roof just for the hell of it or attempt to deadlift over 500 pounds. :p They like their comfort zones, and that's totally fine.
Your mom's just being weird. I suppose a lot of parents will try to pull the "you can't be a guy/girl because of *ridiculous childhood crap*!" card if they're in denial. Thing is, just let it roll of you. Roll your eyes and just be all "You're so weird mom." every time she tries to dig at you. Trust me, it'll get old for her quickly.