Townsendia exscapa is 1.0-1.8", basal leaves, and 11-40 petals. Symphyotrichum falcatum is 0.4-0.8", leaves alternate, and 20-35 petals. Erigeron neomexicanus is 0.6-1.5", leaves alternate / basal, and petals 70-150. https://wildflowersearch.org/search?old ... PlantName=

This flower is ~1.5", alternate leaves, and I counted at least 60 petals. Closest fit is Erigeron neomexicanus.