I'm a GCSE student and for my exam I have to design a children's toy and I wanted a durable, non toxic and cheap wood for some of my designs that could be thrown around and be put into children's mouths without being damaged but I'm really struggling to find a one as different websites have different information.
Take a look at what woods are commonly used for children's toys, and you'll see that a lot of the things made to be mouthed are made of maple or beech. These are both hard, fine grained, and are less prone to causing irritation. Because they are hard they don't dent or scratch easily. The fine grain means that even if they do splinter, they wont form large shards which could cause injury (unlike oak, for example). And finally, they have almost no smell, color, or chemistry that could even potentially cause problems (unlike walnut, cedar, etc).
I would suggest any type of hard wood such as oak or maple. Softer woods like Spruce pine or fir are more likely to splinter in my opinion and that would not be good for your little ones. Make sure you sand whatever you make thoroughly so that it is smooth to the touch. Make sure all of the dust has been cleaned off of it. You can use lemon oil to coat the finished product and give it a clean shine. I would avoid stain and lacker on a children's toy as they may put the object in their mouths and there are a lot of chemicals in wood finishing products.