From photos in CNM, they look like some examples of Amanita sp., but gills cream and apparently not free. Also considered Oudemansiella 'radicata group' but gills and stem seem not right. Mt Painter Reserve Wildflower Triangle flat.
Some Amanitas have 'not quite free' gills. I'll have to modify the brief Amanita description I've put on CNM. Your photos show remnants of the universal veil on the cap (and Oudemansiella lacks a veil) and also a view of part of the skirt-like remnant of the partial veil around the stem. All that helps to confirm Amanita.