Season ends Jan 31 east of I--25. I don't think you will find any wild pheasant or public land to hunt in Boulder county but I admit I have never tried. Besides, season ended Jan 5th west of I-25. This year birds are scarce due to several years of drought. In Colorado, head North East in the vicinity of Holyoke. If you are willing to travel that far I highly suggest going a little further and hunt Nebraska or Kansas. While the bird numbers are down this year you will stand a much better chance of success. Or better yet, think about a road trip to Montana or the Dakotas. Even in down years, those state have plenty of birds.
If you don't want to make the drive think about going to one of the many hunting preserves in Colorado. You will know that the birds are there and you don't really need a dog. Of course in my opinion, hunting birds without a dog just isn't fun.