Mountain Ash

thanks for the help at least I know it's not a fern now

I second the Mountain Ash ID. Best guess is that this is a Sorbus acuparia seedling planted by a bird. Can't really tell unless you examine hairs on the underside of leaflets.

This looks like it's probably a species of Mountain Ash, genus Sorbus, instead of a fern. http://plants.usda.gov/java/profile?symb...