What are the best plants for a shade garden under pine trees?

Azaleas, hostas, gardenias

you may just want to go with a ground cover -- Ajuga would work -- or colorful annual plants in pots .... the soil is not conducive to growing anything that is deeply rooted ... https://www.thespruce.com/grass-doesnt-grow-under-pine-trees-2152742

Ferns, violets, yellow aconites, saxifrage and aubretia, ericas and heathers. You could try anything which is drought-resistant and ground-hugging but please bear in mind that your plants will need watering every day until they are established. Good luck! Sue in England.

Hostas seem the favorite for most gardener's. I would check with your local nursery.

Woodland type spring flowers (trillium, lady slippers, bluebells, wood hyacinth, daffodils, tulips) lily of the valley, hostas, ferns, astilbe,

Hastas...