Up and down, top and side. Not big but small, rolling right along

I come in all shapes and sizes. A gun, a sword, a spear. I turn all men to children if my form is unique. Some people prefer me over automatic.

I guard the fields with a prickly stare, Purple crowns upon my hair. Ignored by hands, yet bold and brave, I flourish where the wild things wave. Touch me wrong and you’ll soon see- What thorny symbol could I be? Want it harder, shorter, or with a mythicalhsymbolic twist?

Your ride or die as you need With horns or wings, I am a mythical being From medieval times to the wild west I was amomg the very best

Some people use my name for a girl. I'm shiny and flat but round like a pearl. If you don't have even me, then you're very poor, yet some think me useless and make me no more.