Wonderwool

Every year the Royal Welsh Showground at Builth Wells is host to a celebration of all things yarn related - Wonderwool was on last weekend, and I was able to get a lift with some other ladies from the local Stitch and Bitch group to make a day of it.
And you do need a day. I'm very organised, and start at one end of the vast hall, and walk up and down the aisles until I reach the other end - and it takes around an hour if you're only glancing at the stalls for a quick recce to start with. When I know roughly what's there, I go back to the ones that caught my eye to have a closer look.
This year I was looking for things I could use for re-enactment. I'm going to my first medieval show of the year next weekend, at Droitwich, and I wanted to have a good display of medieval dyes to show people. I already have madder (which makes red) and weld (which makes yellow). I managed to get St John's Wort (a versatile plant that can make brown, maroon, yellow and green, depending on what mordant* you use), walnut husks (brown), Dyer's Greenweed (yellow, but when used with woad it's half of Lincoln green), cutch grass (yellow), and dyer's chamomile (yellow again). I got all those from the Mulberry Dyer and Fiery Felts. All I'm missing now is some woad for the blues.
One of the reasons I do this is to demonstrate that medieval people didn't go round in mud-coloured clothes all the time. Dye plants were free to pick - all it took was time and a lot of boiling in a cauldron. In fact, peasants were more likely to be wearing pastel shades (because those were cheaper), while richer people wore stronger colours. The word "migraine" originally meant a bright scarlet dye - strong enough to give you a headache!
I was also after lucets, so I can use them to teach the basics of cord making. I got some nice ones from Hedgehog Equipment, and I found a book on more advanced techniques for myself (always stay one step ahead of your students!).

*a mordant fixes the dye so it doesn't run when the cloth is washed. Common medieval mordants included salt and urine!