We had a tent wedding - on a budget. We went to IKEA (which is a great source for things like candles, vases, baskets, etc. and the cheapest I found) plus they take returns if you don't use everything, some places didnt.
Anyways, we had white table cloths and just bought some black fabric to make runners on the tables, to add a little something. Then we put black lanterns with pillar candles in the center of the table, with potted flowers around it. The candles gave off a beautiful glow especially once the sun went down. And the potted flowers doubled as favors.
We were able to do this at minimal cost and it looked expensive and beautiful! At the head table we used just a couple of bigger lanterns and just 2 flowers on each side. It really looked impressive, and kept to our outdoorsy theme.