I am sorry to hear that your pup ate a few choke cherries.
There are a couple concerns with cherries and their pits.
The fruit can cause mild stomach upset simply because it is high in sugar and acid, so she may have some diarrhea.
The pits do contain small amounts of cyanide. But the amount in each pit is very small and if the pits aren't cracked open the cyanide cannot be absorbed. So unless she chewed on the pits and cracked open a lot of pits then cyanide toxicity is very unlikely.
If she is a tiny dog and ate enough of them they can cause a blockage.
So if she's a very large dog, didn't eat more than 10 or so and swallowed the pits whole then she should be fine.
But if she ate a lot and is a tiny dog (Yorkie sized) then I am more concerned.
These may pass but since she just ate them, it may be worth trying to get her to vomit them back up. You can give her 1 tablespoon of 3% hydrogen peroxide per 10 pounds of body weight mixed with bread chunks or ice cream (no more than 3 tablespoons even if she weighs more than 35 pounds).
Then take her outside and run her around to get the peroxide bubbling so she vomits.If no vomiting in 10 minutes repeat the peroxide dose once.
If she vomits and seems to clear her stomach and be done I would check to see if the pits are present.
Once she finishes vomiting and empties her stomach to try and settle her stomach today you can give either:
1) Pepcid-ac (famotidine) at a dose of one half of a 10mg tablet per 10 to 20 pounds of body weight every 12 hours.
2) Prilosec (omeprazole) at a dose of one quarter of a 20mg tablet per 10 to 20 pounds of body weight every 24 hours.
These will reduce stomach acid and should help settle her stomach.
Then feed a homemade diet of 1/3 boiled, lean hamburger or boiled, white, skinless chicken, all fats and juices drained off the meat, and 2/3 boiled, plain, white rice. Add 1-2 tablespoons of canned pumpkin, (not pie filling, just pumpkin), to each meal for fiber whether she vomits most of the pits back up or not to help push the remaining pieces through.
If you don't have peroxide you can get her to an emergency clinic to induce vomiting or you can choose to feed her a bulking diet and watch her closely. In most cases cherry pits do not create a problem because they are fairly small. If she doesn't vomit them back up or you choose not to take her to an emergency clinic still use the bland diet with pumpkin to try and get the pits to pass.
If she doesn't vomit the pits up and in the next day or so she starts vomiting, has a tense painful belly or refuses to eat or runs a fever (more than 103F rectally) then that can signify a blockage and she should be seen by a veterinarian immediately. Surgery may be needed at that point.
But truly this is very, very unlikely to occur.
Please let me know if you have any further questions.