Does my cat have worms? TMI

This such a weird place to post something like this but you all are so intelligent and I would rather hear from someone with personal experience. 2 days ago I noticed something on my cat by her tail. It was this squishy white rice looking thing. It was only two and I haven’t seen any since. Does she have worms? My dogs (THIS IS SO GROSS) sometimes sneaks and tries to eat out of the cat box. If she ate a piece of her poop could she get the worms? Sorry this is super TMI. Also if anyone has any recommendations to keep my dog from trying to eat out of the cat box I would really appreciate it lmao. By the way my cat is strictly indoors and we do NOT have fleas