I've been thinking about what I would do for this contest (obviously won't be entering as I'm the mod for contests!).
For the rainbow quilt I made last year I got out lots of my own scraps, but also got bits of fabrics from my mum and Auntie, left over from their projects, Auntie in particular was a goldmine as she's been making clothing for herself, kids, grandkids and others.
I noticed that there were a few pieces in the blues section (her favourite colour) that could work together nicely for a multi fabric shirt, with maybe a few other bits added in.
After a bit of a search I found 5 pieces which sort of work together, the smallest ones at the top (red/white paisley and red strawberries) could only be a cuff or collar, the middle ones (the two spotty ones) a front or sleeve, and I think the back and anything extra will be from the bottom fabric as I have the most of that one (though still not enough for a whole shirt).
The blue with white spots has a slightly different hand to the others, so although it works colour wise it may get dropped.