This picture, I am almost 100% sure, would have been taken at the conservatory in Glen Oak Park in Peoria. Nan and her friend (I think she was a girl Nan worked with at Powers Camera Shop) are admiring the lovely blooms. Nan is holding her hat which looks as if it were trimmed with a lovely flower and she is wearing a pretty summer dress with three-quarter sleeves trimmed with lace and a big sash. I would guess the dress is white and sash blue. Her friend has a lovely plaid skirt and white blouse and straw hat with a halo of flowers around the brim.
This most likely was a lovely summer afternoon and the girls had been for a walk in the park.
(Click to enlarge)