Nothing good comes from cemetery energies. Things go there to decompose. And although not many, lost spirits there can easily attach themselves to us without the proper protections. As a palero, our godfather has specifically prohibited us from going even near cemeteries, which is very unconventional from other branches (outside of funerals and visiting loved ones). In Palo Mayombe for example, lots of work is done in cemeteries, from looking for spirits for an Nkisi/Nganga/Matari, collecting soils, to malefic work. In the branch that I'm part of, Palo Monte, we're of the belief that spirits are everywhere. There's way better places to find spirits and collect materials for malefic work. But that's a separate topic.
Now in terms of collecting plants like in your case OP, I would be very cautious. One of the places that spirits love to inhabit are plants, more so trees. It's possible to bring home a plant from a cemetery with a spirit attached. Like others have said though, you can cleanse the plants to hopefully rid them of any accompanying energies. But really, I would be more worried about something attaching itself to your astral body while in there than something that may come with a plant.
People are obviously free to do as they wish, and my viewpoint is solely mines. But if for any reason, anyone finds themselves wanting to visit a cemetery for anything, even funeral services, here's some steps to take:
- Wear/take some type of protection. Whether it be amulet, crystals, stones, plants, anything helps.
- Bring an offering. Florida water, rose water, rum, tobacco, coins, etc.
- Bring a bag, preferably black. Grocery bag, paper bags, etc.
- Before entering, invoke your spirit guides, protectors, and ancestors. Knock at the entrance 3 times and ask the watcher of the cemetery for permission while stating your purpose. If you have a divination device, like a pendulum, shells, bones, chamalongos, anything, use that to confirm. Or use your mediumship to get your answer. If denied access, yeah it sucks but give thanks and walk away. You can try another day or place.
- If collecting something, when finding it, ask for permission for that thing. If granted, respectfully collect the material, give thanks, and leave the offering.
- Place the item in the bag. If driving, stick the bag in your trunk.
- Before going inside you house, leave your shoes outside. These should be cleaned with Florida Water. I'm actually planning on a post with a spray cleanser that's super useful for that kind of stuff.
- Wash the items with Florida Water. Maybe do some more divination for further confirmation that the item is accepted into your space.
- Give yourself a cleanse of some form. Whether with Florida Water, smudge, tobacco, preparing a bath, or a combination. You can't be too safe here.
That should help ensure that you personally don't bring anything home with you. I would personally get rid of the plants but if you wanted to keep them, give them a cleanse and ask your protectors to help remove any unwanted vibes.