This one has many names, Oncidium pumilum, Lophiaris pumila, etcetera. I go with Trichocentrum pumilum.
I've had this plant for almost three years and this is the first time it flowers. I think the magic was to put it outside 24/7/365 and give it a cold winter and cold nights - bam! 4 spikes! I broke one when it was small and brittle, I didn't even see it. 3 are left and the first one is starting to flower right now.
I grow it mounted on a piece of oak, where it has been for about 2 years. I had it mounted on cork for a while before that, but I prefer this stone hard oak that lasts practically forever. I water it every morning through an automatic spray system, though now I've put it on display so I spray it manually in the morning.
The flowers are about 3mm diameter and very difficult to photograph with the telephone. They are still just about opening up and I expect a "yellow branch of flowers" when they're all open. I will try to take some better photos of it with a tripod and camera.
Not a spectacular plant, but I'm so, so happy that I finally got it to flower!!