Does your back yard get flooded from the rain or your neighbors watering. We have clay on top of hard pan & our back yard partially slopes. Anyway my dad did something like this years ago & it helps.
DIY Retaining Walls are pretty suitable for a yard, a garden, as they can change the whole dynamic of your space. A garden or yard retaining wall might be a necessary feature.
Walk out deck
Do you have a permanent damp spot in your yard? Do you always get water in your basement after a heavy rain? A French drain might help dry things up. Here are the basics.
Easy DIY project: Pallet Outdoor Bar Pallet BarsPallet for Outdoor Project