If she has no signs of discomfort and it's just a swollen eye, I would keep an eye on it at home, and take her to vet if it appeared to be anything more serious than a simple bruise near the eye.
If your dog's eye is swollen shut, that could be more than just mild irritation ior bruise. If there is dicharge and the eye is red, it is probably that the mild irritation caused an infection of the conjuntiva, or conjunctivitis. This requires antibiotic ointment or drops to clear up. It's a simple treatment, but if you leave it untreated you may cost your dog his sight in that eye.
Personally, I would take her to the vet... it most likely is nothing but then again you never really know. I guess it would depend upon how much your 'peace of mind' is worth to you? If you do wait a day and there is no improvement, then I would surely take her to the vet.
this is really after the fact by now, but thought I would chime in with what I have experienced. Weed seeds. If they get in the eye it is almost impossible for you to get them out yourself. you can look by rolling the eyelid down but keeping them still, much less trying to get in there and get it out is really difficult.. I have had two trips to the vet with this. I know keep the eye solution that you use for contact lenses handy and flush eyes out with that when they have been running in tall weeds...