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