A blog reader, SuzOH, sent an email identifying my mystery plant as Lotus maculatus commonly known as Golden Parrot's Beak.
We saw it on a trip to Kansas City and had no idea what it was so I put a photo of it in my June 10 blog entry. Happily a reader recognized it.
Backyardgardener.com (click here) has the scoop on how to grow it. Warning - the site has constant popups that you have to click closed in order to read anything. They say it tolerates heat and humidity and is cold hardy in zone 9.
I searched online and it looks like the vendors are mostly in England.
Wikipedia's photo shows the plant trailing out of a hanging basket. Those hot orange.red flowers don't show at all from this vantage point.
At Overland Park Arboretum they were at eye level so you could enjoy the flowers.
Have you seen it at your local nurseries? Do you grow it?