When selecting a Peony choosing one which has the RHS garden merit award is always a good guide. With the RHS award and illustrated above (centre) is the lovely showy red flower of a Peony officinalis 'Rubra Plena' . Also with the RHS award is 'Bowl of Beauty' which has lovely delicate pink petals with a dense centre of creamy white, illustrated left; P. 'Duchesse de Nemours' which has large fragrant white flowers; P. 'Sarah Bernhardt' lovely double rose like pink flowers which scented and illustrated above right ; and P. 'White wings' also scented, and as you can imagine white a single flower with yellow boss.
Crocus have over 15, excellent showy varieties of Peony for sale, including many mentioned here. Click here to link to Crocus Peony selection.
Peony flowers come in four shapes: a single flower head which has a large central boss; semi double, which is similar to a single but with more petals; double which has more petals, often ruffled, filling the centre and with no discernible boss; and the anemone form which has single or semi-double flowers with the centre filled with petaloids, such as in the 'Bowl of Beauty' which makes it very attractive.