For example in the 3rd card in this post, the particular person that I was making the card for really liked the chevron pattern, and I had nothing of the sort in my stash. I went online and found a free printable: Chevron Free Printables by Mel Stampz (Thanks pinterest!) I printed it out and used it as a background. I totally loved how it came out and since I printed a whole page of it, I can now use it for other cards.
Also before I throw out anything, a catalog, a calender, or a gift bag, I look at it and see if there is anything that might be useful. If I find something, I cut it out and throw it in my supply bin for later use. The rose in the first card is actually from the back of a calender.
Basically, if you don't have it, there is probably a way you can get it... you just need a little a little creativity and ingenuity.