A fun series published by the Gibson Art Company is a birthday series featuring girls dressed as different flowers- daffodils, lilacs, roses, etc. The one to the left is a girl I believe dressed in either forget me nots or blue carnations. The girl on the right looks like a rose.
The cards are signed by M. Dulk, who is not as prolific as Clapsaddle, Dwig, or Twelvetrees. If you search for him/her on eBay, you’ll only get about a page of things for sale at any given time. The reason I say him/her is because I always thought Dulk was a man, but I saw someone advertising a card from this series as being signed by Margaret Dulk. When I searched for Margaret Dulk though, that was the only page that came up, so I believe that person is incorrect. I’ve seen it happen before- people say postcards are signed by artist “Helen Twelvetrees.” Helen Twelvetrees was an actress.
The blue girl was postmarked 1920, and the red 1915. I have several others in the series as well. The one I really like but don’t have is a girl dressed as a daffodil.