The points of contact are mainly in the first part of the poem. Roses, blush, shame, lilies, hands, violet, purple, dyed, flowers, sweet and breath are common to both sonnets, a list which seems to outdistance the probability of mere coincidence. Shakespeare probably remembered this Constable sonnet, consciously or unconsciously, and used elements of it when writing his own. The theme was tradtional and comparison of one's beloved with the beauty of flowers was not new. It is more likely that the unconscious memories fused themselves in Shalespeare's mind and produced his own unique product from the basic elements.
Violets are a flower of early spring, found in copses and on roadsides.
Sweet thief, whence didst thou steal thy sweet that smells, 2. The violet was noted for its perfume. The purple pride 3. The colour was associated with imperial garments in the court of Rome and elsewhere. Hence purple pride means something like 'glorious purple, imperial glory'. 4.