This isn't a real playground, but it has lots of great ideas.
52 DIY Pallet Signs & Ideas with Great Quotes - Big DIY Ideas
24 x 29 Bless the Food before Us The Family by DesignsbyRhondaLynn
Rustic Reclaimed Wood Sign~FAMILY sign with Clothesline Wire, Rustic Home Decor, Wall Decor, Family Sign, Reclaimed Wood Sign, Wall Hanging by CSquaredCustoms on Etsy https://www.etsy.com/listing/230378846/rustic-reclaimed-wood-signfamily-sign
A personal favorite from my Etsy shop https://www.etsy.com/listing/232752614/family-where-life-begins-love-never-ends
House Family Rules wood pallet sign by southerncutedesigns on Etsy
What a fun & inexpensive way to dress up your backyard, and get some much needed seating too ...
How To Build A Backyard Swing Set
http://www.woodesigner.net offers great guidance as well as ideas to working with wood