Lewisville Park is a quaint a beautiful park, one of two major parks in the Battle Ground area. I personally recommend this one over the other option, which is Battle Ground Lake State Park. Lewisville Park is just more relaxing and has a better atmosphere and much better scenery. There are picnic benches there scattered across the edge of the water where you could sit and chill and have a good time. The wildlife is fairly abundant there and no one will bother you, plenty of privacy. The other thing to do while you’re in town is visit any of the four wineries.
There are a few things a stoner can do in Battle Ground yet visiting the Wolf Park is a must. Considering you get there on a Friday or Saturday, you can get a combo ticket for a discount and visit the park twice in the same day. The point is that the wolves are not very active during daytime, so when you return at night (after having enough time to hit the bong) you can witness an wolf howling concert. Later, you can check into Battle Ground Pizza King, a small and intimate place where you can eat really good pizza, bread sticks, garlic bread and others. The staff is very friendly and the food is ready in no time so you will probably want to come back.