I am fairly confident these are Armillaria straminea (var. americana, according to "Mushrooms of Colorado and the Southern Rocky Mountains"), but I certainly welcome any confirmation/denial of this. The first 2 photographs are of a larger specimen, about 12 cm across. The 3rd photo are smaller, younger ones, 4 - 5 cm across. The book also says they are edible and Mushrooms Demystified notes that A. straminea is said to be a popular edible mushroom in Colorado. (I live in northern New Mexico on the Colorado plateau, so same thing). I took the larger one home to look at it more closely and left the younger ones. The larger one was definitely past its prime and even though it is classified as edible, I think not at that age. I am drying it though, just to see how it holds up to that process. The smaller ones, though out of focus, may be more edible. I guess my question is, before I attempt to eat these, has any one out there eaten them? Oh, MD also notes it is also called A. luteovirens.