I am frequently covered in various bruises, feeding times I'm basically a human skittle. Get in amongst sheep with a bag of food and you'll know about it. Willow has terrible spatial awareness issues and has frequently hit the back of my legs with the force of a truck trying to get to the food. Put it this way, they won't stand on ceremony.
The smaller varieties of sheep will also jump up, it's not been uncommon for me to be wandering about with muddy hoof prints on my bum. And they will quite often ask for attention, or a scratch, in the only way they know how, which is a friendly butt.
A friendly butt is uncomfortable and non friendly one bloody hurts. Mitten did go through a really odd aggressive stage to the point I had to take a shepherd's crook with me when I went down because the possibility of my leg getting broken was quite high. I need to point out here, in case people jump to conclusions, a crook is not used to hit sheep. It's used to catch them, or guide them, or in my case I'd use it in front or behind my leg as a block.
Mitten is a wether - castrate - so considerably less aggressive than a ram, and rams can do you serious damage. It always concerns me a bit when I hear knitters dreamily planning flocks of sheep for the purposes of making bespoke yarn, and I would implore you please spend time with someone with sheep before jumping in. Sheep are strong, they can be boisterous, and keeping them often isn't as easy as you think. I have known people start a flock and those animals quickly end up advertised and probably in someone's freezer.
Sheep have a hierarchy within the flock and will reinforce this by shoving each other and I often see mine play fighting. Even ewes will happily shove each other out of the way, and older or ill animals bear the brunt. Some sheep can be bullies to others just like chickens can.
I do like mine to see me as the source of something good, so they get treats. Just be warned if you do this they will start to mug you, chew pockets, and in my case last night Parsley got over enthusiastic and bit my bum. Sheep may only have bottom teeth but it still hurts! Normally if I was clicker training I train animals not to mug for food, but it's very difficult to separate sheep to give you the necessary space to do this, so I'm aware what hand feeding can lead to. You must make sure to never reinforce that behaviour.
So next time you pass a field of sheep just remember, they're not always the benign woolly things you're led to believe - sheep bite too!