Dodecatheon jeffreyi is a perennial herb in the primrose family that produces its main display in spring. Flowering occurs from April to June. It prefers full sun or partial shade and thrives in moist, well-drained sandy or rocky soils. The species originates from western North America.

Giant American Cowslip (Dodecatheon jeffreyi) flowers April to June and suits full sun or partial shade in moist, well‑drained sandy or rocky soil.

https://en.wikipedia.org/wiki/Primula_jeffreyi

Primula is a genus of herbaceous flowering plants in the family Primulaceae. They include the primrose, a familiar wildflower of banks and verges.

Dodecatheon jeffreyi

Giant American cowslip | Dodecatheon jeffreyi

Dodecatheon media is a perennial herb in the Primulaceae that flowers from April to June. Native to North America, it favours moist, loamy, well-drained soil with a neutral to slightly acidic pH and grows in partial shade to full sun. Rated H5 (hardy), it performs best on north, east or west aspects with sheltered to semi-exposed exposure. It is well suited to woodland gardens, naturalised areas and borders.

Shooting Star (Dodecatheon media) flowers April to June and prefers moist, loamy, neutral to slightly acidic soil in partial shade or full sun.