I have too, many a time. I imagine that, like me, you'd make sure you took some from an arey where there are 1000s, and you just take a little clump here and there...
Also divided and given away so many to friends- and received some back in return too. (very different to nicking some very carefully planted in a park or public amenity though).
My dad brought us a daphné taken from the wild here in Switzerland, for our Midlands garden. It was my prize possession for about 20 years- but one year it died. Never had another one since. They grow wild here and I just love to see them in bloom in the snow, and the smell is wonderful.
Once we visited the grounds of my bil's business and the gardener had dug up all the day lilies from the beds- to weed and replant later. My bil was quite annoyed that I took a little clump ... but now about 40 years and 4 gardens later- I've still got several good clumps, and have given much to neighbours and friends- and some has even found its way back to the UK and bil's garden. Still a family joke today.