A goodly crop?

When I was just starting my (nearly) raised beds; I put a bale of straw, split up, into the bottom of them.  A couple of years ago I had a crop of wheat from them.  Don't let them set seed "he" said; I needn't have worried the birds made sure of that.
I wonder if they'll do the same for these oats.  
What I can't understand is the clump of them.  I've never had oats in the house except as Porridge and certainly have never thrown a handful of oat seeds onto the garden.  Can you get such a clump from 1-2 seed dropped by a bird &/or hidden/planted by a coal Tit.