Here in Naples, Florida they are considered a type 2 invasive. I love them and have around 25 of them and they pretty much will grow in any type of medium other than sphagnum. I have grown them in regular potting soil with some perlite added and also in orchid bark as well as plain old mulch. What you could do is mix some mulch and leaves together, plant them very shallow on top of the soil and cover with leaves. I have found they love to grow under landscaping where the leaf matter is blown under the shrubs.
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Oh and they tolerate just about any amount of water. You really cannot kill these things.
From the description, I agree with K.o.o.g., they are likely O. maculata, which is a non-native invasive species. A photo of the plant would confirm this. Can you take a picture & post it?
If that is what they are, no harm in keeping a few for your garden, but don't be too concerned if the goats trample the rest.
I have one in my yard,transplanted it to a place where I can see it. However, mine is not invasive at all and at the most manages to send 1 or 2 spike once a year. I like it's leaves though.