Annie's next training exercise: Learning the pick up the right one. 15 minutes a day for a week should do it...
I'll start out by using a clicker and clicking when she noses each one, while saying the name and giving her a treat. Which reminds me - there are some who disagree about using treats because they think the dog is being bribed, and will learn not to work for it unless a treat appears. Annie is smarter than that. Over the winter, I wore a poncho and the pockets were stuffed with treats while we nailed down the "Come" command. I don't wear it very much now, sometimes in the early morning. When I'm not wearing the poncho, she does not expect or look for a treat. But if I do wear it, she comes right back after pooping, without her ball, straight for the pocket of treats.
She no dummy.