I use a flannel-backed tablecloth meant for picnic tables. On grass or sand, it's put plastic-side down so you have soft to sit on. On rocks or a real table, I put the plastic side up. It spot-cleans with no problem. In fact, a small one lives in my car trunk to protect the carpeting from various pots and plants that may drip or leak dirt; I just toss it into the washer when it gets really awful.

If you want a softer seat, use your old blanket as a liner between two of tablecloths.

Also, my local $-store has plain plastic tablecloths which are quite sturdy. Hard to beat that price, lol

Meldy's suggestions are the inexpensive way to go, but they also make special outdoor blankets which meet your criteria. In fact, department stores are probably clearancing them with their seasonal items (think overpriced picnic baskets with lucite wine glasses and decorative bug candles).

Steve's company gave him a blanket similar to this as a gift (the woman in charge got tired of chasing down shirt sizes) and it's nice because nothing sticks to the side that goes down and it rolls up nicely in a package that doesn't allow the blanket to get dirty when not in use.

I know you can get one cheaper than the one I linked to, and this is the perfect time of year to do so.

Well since the trunk of my car currently is littered with fertilizer particles from a bag that ripped and bits & pieces of potting soil (ditto), I obviously am not as particular. I've got a couple of (very) old blankets that sit in plastic bags in the garage that I use for this purpose. They're washable so I just throw them into the washer after each use.

However, it stray grass & weeds bother you, using the dollar store table cloths as a liner under your blanket seems to be the way to go.

I'd sandwich the blanket in between 2 bed sheets and quilt them together. I made my quilt like that but one of the sheets was satin.

It was interesting reading about other's creations/techniques. I'm so busy right now trying to get my private practice off the ground that I don't have time to make something. (But who am I kidding--even if I did, I probably wouldn't have the inclination, esp. with something like this so cheap! :-)

I looked online and saw what Michelle was talking about and realized I also want something with a pattern on it, but it was eye-opening to see this specific thing is actually made. I /really/ don't get out to stores much due to a strong dislike of shopping.

Well, I called a bunch of dept stores in the area and got several variations of 'huh?' then I hit on the idea of trying linens and bb&b. The latter said they had some, I went over and found the perfect thing! It folds up and zips together to form its own pouch. Has a carrying strap, a pocket for Stuff and a really cute pattern. I can hardly wait to try it out at an outdoor concert later this week!

Thanks again for all the brainstorming!

Leaves, so glad you found your "perfect thing". May I ask what your private practice is? Aren't you located in the Cities?