Ragwort ......

..... has a rather patchy welcome.  It is loved by many insects, and essential for the cinnabar moth (or more accurately, for its caterpillars).  It is toxic to horses - but if it is growing in a field of grass, the horses recognise its toxicity and will avoid it.  However, if it is harvested and made into hay, they don't recognise it in the same way, and that is when the problems arise.

I think it is a glorious yellow, but I am aware others think it is a brashy plant.

We've never planted any, but it has made itself at home in our garden in previous years.  We only have a couple of small plants in our meadow this year, they were very late to flower, and there's no sign of any cinnabar caterpillars.