I have many, but only use the following now because the glues are so good. There was a time I would mix flour and the bottom of a jar of shellac and take the thick goop from the shellac and mix that, the fine flour and some sawdust, occasionally adding glue.
I also use Timbermate brand filler if what I have matches the wood. I usually mix a little colored sawdust in it though. I have a neutral Timbermate I can mix with sawdust to make custom darker colors that Timbermate does not make off the shelf.
The simplest is just mixing the saw dust with Titebond III, which works surprisingly well, but its not the best for a light wood like Maple.
I also use 5 min Clear Epoxy I mix with the saw dust.
Nickao