You should probably check to see if there is a hole where a button might have been. However, it does remind me of an older teddy bear that was filled with sawdust, I think it was a Dakin, but not positive. They did have the little tongue thing, and a label on one left foot. Might want to follow that up, as Dakin made all different sizes and types of teddy bears.
The best way is by feel. If it is soft and spongy, its not sawdust. If it is stuffed with sawdust (and sawdust shavings), when you squeeze it, it kind of feels scrunchy/crunchy.
Oh, and another identifying factor is what it has for the bottom of his feet - felt was used at times, and just the same fur on feet as on body on others.