I'm with the others. I don't think they are all that mismatched in size, some can be trimmed down a bit. No one is really going to notice if the background is 1/4" closer to side, or if the framing is 1/4" larger or smaller. To be specific, I would frame each block and then center them and trim them to the same size. You can use the same fabric or different ones, I think a busy small scale floral would work very well. I would then use a fairly thin sashing, in a close enough to the green or background.
The other option would be to use most of the blocks that are closest to size. For that I'd set them on point and alternate with a full sized block of probably the "close enough" green since it won't touch.