My friend and I recently checked out Pleasant Valley Nature Preserve near High Ridge, Missouri. It is a smaller area, but has several loops that you can connect to hike for as long as you want. I forgot to take a picture of the trail map that is posted as you enter the preserve =)
After starting out from the parking lot, we made a right and started on Loop A and then connected to the back half of Loop B. This part of the trail contains several switchbacks which leads down to a small valley with a pedestrian bridge.
Just on the other side is a fenced off area which contains a sink hole. We noticed several sink holes in this area.
We continued on to Loop C, essentially hiking the perimeter trails.
Once arriving back at the main area which contains a pavilion and restrooms, we hiked Loop D which is a smaller loop, but seems to be the highest point in the park. There is a bench at the top of the loop so take a break and enjoy the experience.
We kept this hike fairly short overall. This would be a great hike for kids as the trails are mainly gravel and pretty safe. I enjoyed this nature preserve so be sure to check it out! Dogs are also allowed!