This appeared as undergrowth in a pot of clematis a friend gave me about two weeks ago. Other things appeared in that pot too, but this little yellow one is something I'm not sure about. It grows in clumps, has a sort of woody stalk, and grows from runners. The blooms are tiny, about the size of the tip of a pencil eraser. It has no scent. The clumps are small and compact, as it blooms the stalk grows taller, but it's only about 6 inches tall even then.

I thought it was a Wallflower at first, but I'm not sure. Someone else suggested Crown of Thorns.
It's something I've known in the past, but is only vaguely familiar to me now. I hate when I forget things like this.

It's not Crown of Thorns, of that much I am pretty sure.
It's cute!

It looks like a wallflower to me Sharon, Erysimum. They do grow from the previous year's old wood sometimes, but don't make good plants so they are usually treated as an annual.

Does that mean it won't grow very well in ground or in clumps, Janet?

The friend who gave me the pot of clematis didn't tell me all this undergrowth was there. In two weeks I've suddenly had hyacinth blooming, this little yellow thing and tulip foliage all in the pot with the clematis. The friend isn't a plant person, so when I asked her about the new growth in addition to the clematis, she had no idea what I was even talking about.

The pot of clematis has been outside for years, she said.
And that is about all I know.

Surprise blooms! Love those

It has been fun, Tarev!

Sharon said:Does that mean it won't grow very well in ground or in clumps, Janet?

Wallflowers grow well in the ground but don't come back every year nice and fresh, some will regrow but as you have seen with yours the old stems don't make a good plant. They are best dug up and replaced with new plants, something I don't want the bother of but it used to be a popular bedding plant here. If you really like it you could see if it makes seed and grow some new plants, the one you have is trying to give a good show so you could just enjoy it while it lives.

Thanks, Janet!