You might have success with fragrances that declare notes of datura and tobacco blossom if nicotiana and petunia are not listed. Datura has the sweet/earthy spice of petunia as well as the warmth. It is, however, not as sharp. Could you describe the nicotiana flowers that you remember as a child? Nicotiana has several varieties and each has a different scent. I have grown N. alatis, N. sylvestris and others and each has a signature fragrance. There is, however, a binding note to them all and it is the rich sweet warmth of tobacco.