I entered this image to be considered as a stock image, this image was taken with a Canon t3 and I have not resized the image to reduce quality, however, quality is why they rejected it, any tips? Would it be because the background is too dark? my focus on this image was the inside of the flower, not the surroundings so not sure why it wouldn't be accepted.
see here for technical and quality reasons. As modifying the original picture may degrade quality, it may also enhance the image. So doing no touch-up is not a guarantee for a good quality image.
Shooting RAW and developping that raw picture generally gets you better results.
I think you have cropped the image too tightly - composition, you should leave some space around the flower. The lighting is too harsh as well. You have strong shadows! (Taken with a flash no doubt.)
It may also have too much contrast. I also think there could be some focusing issues, but a bit hard to tell at this resolution.