A dog will naturally use their mouth like we use our hands and so will pick up interesting things, like sticks, from time to time with their mouth. That's normal behavior in any dog and hard to correct for.
She may also be teething, though it seems a tad early. Nevertheless, a teething puppy will chew and chew a lot. Much for the same reason we did the same, the process of the teeth coming in is uncomfortable. If you have some good chew toys available for her, then that may distract her from some alternatives. In any event, if she is teething then be careful not to grab her mouth and try to avoid getting into the habit of letting her mouth people if she starts. Just disengage her from the undesirable chew subject and give her a toy for that purpose. After a while, she'll gravitate to the toy.
However, with respect to some of things she's picking up, there may be some cause for concern (I don't intend this to be alarmist though):
Feces carry some risk of parasites. While, it's also normal for dogs to eat the feces of other animals (Karen Overall - Manual of Clinical Behaviour Medicine for Dogs and Cats) you should get her checked about every 6 months or so to make sure she hasn't picked up something.
More pronounced behavior of this sort is commonly seen in dogs raised in a puppy mill or in pet stores where they haven't been fed well. Not uncommon, sadly, when the goal is to keep the dog smaller for sale purposes. If you know for sure this isn't the case, then just keep an eye on her health as I mentioned. If you don't know, it's probably a good idea to speak with your vet about other possible issues for a mill-raised puppy. Carefully handled with early and they shouldn't remain a problem.
The last two points are long-term items to consider. Like I said, I posted them to make you aware, not to be an alarmist.