Yes...you can do this...I do it all the time. Divide them as you would any plant. Especially Coreopsis and Yarrow...they are like weeds. Just keep them moist until they form new roots and can survive on their own then back off the moisture until you are not helping them anymore and you are all set. Pick a spot in your yard where there is sun all the time for those plants...they love the sun. What varieties? Pictures?

I've got two each of lanceleaf coreopsis and two of the moonshine Yarrows. Should have known they weren't doing too hot when the Yarrow that gets sun first is twice as big as the other. I'm glad that I got another green light. They'll look good up in my 'wildflower' bed with some natives I've been digging up here and there (mainly phlox, spiderwort and verbena I've been finding around my neighborhood).

Thanks for the help!