This was the response from our Iowa State Extension and Outreach horticulture specialist.

There are not many plants that resemble the look and especially the smell of dill. The photos you’ve shared do look like dill, although seeing the flower will help confirm more conclusively. It is not possible for me to identify this plant with 100% accuracy from photos, but if it looks like dill, smells like dill, and you’ve planted dill there in the past, its likely dill. As with any edible plant that is not 100% known, try it in small amounts to be sure that no one has a negative reaction to it before using it.

There are not many plants that can be easily confused with dill and those that are often confused with this plant are not toxic. Other plants that closely resemble dill include fennel (Foeniculum vulgare) and anise (Pimpinella anisum). Other plants have ferny foliage like dill but a much different growth habit and/or flower include, chamomile (Matricaria chamomilla) , false chamomile (sometimes called mayweed) (Tripleurospermum inodorum), pineapple weed (Matricaria discoidea), asparagus (Asparagus officinalis), and asparagus fern (Asparagus aethiopicus, Asparagus setaceus, or Asparagus densiflorus).

Happy gardening!

--Aaron

It appears that the photo of the flower you tried to upload was too large, so it didn't upload.  If you'd like to try again with a smaller file size, I'll take a look at it.

The flower looks much like dill.  Its hard for me to say with 100% certainty if a plant is edible by looking at photos alone, but the foliage and flower both look like dill.  Because it looks like dill, smells like dill, and you’ve planted dill there in the past, its likely dill.

As with any edible plant that is not 100% known, try it in small amounts to be sure that no one has a negative reaction to it before using it.

 Happy gardening!