You may be on to something Lindsey. I do agree that #3 looks like it could be Dendrobium Lindleyi/aggregatum. In fact, it may even be the smaller species jenkinsii.
But Gina, identifying unknown plants from bulbs and leaves is nearly impossible! You got lucky because one species in particular has destinctive enough growth that we could venture an opinion.
They could benefit with a bit more water as the middle plant looks more distressed then the other 2. It should be remounted with a little long fibred sphagnum moss behind it.
The same can be said for #1. It is naked essentially on a tree fern slab. A little pad of moss would help it tremendously. It looks like a small Oncidium, perhaps flexuosum, but it could be Maxillaria variabilis. It is just way too generic at this stage. But it is not a Dendrobium.
Have they ever bloomed for you? If so, an image of the flower would be a big help!
It also appears that in photo 3, there is a second plant on that mount. Mixed in among the broader, rounder leaves are some longer, lanceolate leaves, one lower right and 4-5 upper left.