Growing anything under white pines and spruces is tough, and acidity is not the only issue. These conifers produce such a fine mass of roots close to the soil surface that anything else trying to grow in that area has to compete for water and nutrients. Thus other plants often tend not to do very well in this environment. You will need to provide good moisture, and fertilize during the establishment period in order to get them off to a good start. Root pruning of the white pine can help, but don't cut out an area larger than 5% of the root zone at any one time.
A partial list of plants preferring acidic soil includes: Amaryllis
Andromeda
Aster
Azalea
Bayberry
Bleeding heart
Blueberry
Camellia
Clethra
Dogwood
Evergreen
Fern
Fir
Gardenia Heath
Heather
Hemlock
Holly
Huckleberry
Hydrangea
Inkberry
Juniper
Leucothoe
Lily-of-the-Valley
Lupine
Magnolia
Marigold Mountain-ash
Mountain-laurel
Oak
Pachysandra
Phlox
Pieris
Pine
Raspberry
Rhododendron
Spruce
Strawberry
White cedar
Woodsorel
