What to sit on in the woods

My 2.5 year old daughter and I have been going on lots of nature walks in the woods lately. I bring the jogging stroller but oftentimes she gets out and walks too. The thing is: she stops often to look at sticks, play with rocks, sit down, smell flowers; etc. So sometimes I’d like to sit down too because she can take a while.

Any ideas on what I could bring to sit on? Something small (that I could fit under the stroller) that I don’t have to worry about folding up each time she stops (there are many stops!) maybe something water proof? Easily washable or somehow otherwise disposable?