I first found these interesting little flowers years ago in a wetland area. The plant likes moist soil.
The interesting little flowers next appeared along the road at a cold water spring. And this year they are in a runoff ditch down the road.

Each year I put these interesting little flowers in the Unknown folder with the name Ears. Each year I search for an identification and fail to find one.
The plant is about a foot tall with multiple stems and branches. The stems are thin so the slightest breeze shivers through the plant. They are covered with short hairs.

The leaves are opposite. The petioles are about a third the length of the leaf. The petioles are hairy. The leaves have no hairs.
Flowers are on stalks from the leaf nodes toward the ends of the stems. Looking head on two larger petals stick up (my ears) and two smaller ones hang down. Each is separate from the others. The flower is maybe half an inch long.

The flower extends from inside a cylinder covered with sticky hairs. This led me to think, since Royal Catchfly, Fire Pink and Wild Pink flowers are similar, perhaps this flower was in Caryophylaceae. I looked up pictures of all members of this group found in Missouri and came away disappointed.
The seed capsule forms inside this sticky cylinder. When the seeds are ripe, the cylinder splits to release them.

Finding these interesting little flowers is always a treat. They are much too pretty to be stuck with the name ears.
I am again trying to find these flowers on the internet. I am still having no luck.
Perhaps someone recognizes these interesting little flowers and can let me know what their name is. I would like to solve this long standing mystery.
Identifying Missouri milkweeds is easy with “Missouri Milkweeds, Milkvines and Pipevines“.