It's the pile of scraps and pieces I've been tossing aside when I've made failures I felt I couldn't back out of. Luckily my skills at "retro-tatting", as one Craftree forum member calls it, (that's meticulously picking out mistakes), have grown and that means less and less thread is being sacrificed to the scrap heap. I'm likely making almost as many mistakes, usually the result of a moment's foolish inattention, but now I spend ages picking the errors out rather than tossing the entire piece away in frustration.
Just thought you should know in case you're giving this a try and judging yourself harshly based on your perception of my progress. Ha!
But for all those errors I do keep persevering. Tatting is challenging, fun, and occasionally there is a worthy end product.