They could be a mountain ash, they're very prolific. A picture would help a lot.

you either post a picture or 2 ....

or google both names and compare what you have ....

i will link to the first for you

ken

Here is a link that might be useful: change the search to M Ash

If they are walnut, you can dig a little bit and easily find the shell of the nut. Shouldn't be more than a couple inches below the surface, and likely still attached to the seedling. Also, it's in the back of my mind that walnut leaves have a distinct smell when crushed. Just rub a leaf between your fingers, and compare to the mountain ash or walnut.

Alex

If you have several that have come up really close together, I think they are probably ash. Squirrels would have buried the walnuts, and I don't think they'd put that many in the same place. I find pecan trees all the time that they've planted, and there are never more than one in the same place.

Around these parts, mountain ash-not an actual ash tree but rather, a member of the rose family-can and do occasionally show up volunteer-style. On the other hand, squirrels absolutely go nuts-pun intended-burying black walnuts this time of year. So as far as the likelihood of it being one or the other, I'd rank it a toss-up. The compound leaves of both species do have a superficial similarity but if you can goog up some pics of each type of leaflet, you should be able to discern which it is you've got there.

+oM

Not sure about walnuts, but I know squirrels bury acorns in clusters, as I've often seen more than one in a group.

Sumac and Ailanthus would be considerations as possible 'volunteers' here, as well.