When you do a search on Google Images (let's say for "wood") you can change the Usage Rights to a couple of different options. You'll find it by clicking on "Search tools". You'll probably want "Labeled for reuse with modification" most of the time. Give it a try right now. There's also a search on the Creative Commons website itself. It will automatically search Google Images with the setting. The Internet Archive may have some things you want. And, of course, if this is a hobby you want to do long term, you might want to look into buying a scanner and digital camera someday. More on reddit.com

Because blogs come and go, here it is on reddit for you to save. Also, pastebin http://pastebin.com/BK04yd4r Free Photos Unsplash – free pics under Creative Commons Zero CC0 License https://unsplash.com/ Gratisography – all photos licensed under the Creative Commons Zero (CC0) license. http://www.gratisography.com/ Pexels – all photos licensed under the Creative Commons Zero (CC0) license. http://www.pexels.com/ StockSnap – all photos licensed under the Creative Commons Zero (CC0) license. https://stocksnap.io/ Splitshire http://www.splitshire.com/ Life of Pix- all photos donated to the Public Domain http://www.lifeofpix.com/ I'm free - Curated free design resources http://www.imcreator.com/free New Old Stiock - Vintage photos free of known copyright restrictions http://nos.twnsnd.co/ Pic Jumbo - Free images to your inbox https://picjumbo.com/ Death to the Stock Photo - Free Photos to your inbox each month http://deathtothestockphoto.com/ Getrefe – Free photographs http://getrefe.com/downloads/category/free/ Snapwire Snaps – Tumblr Blog of free photos under Creative Commons Zero License CC0 http://snapwiresnaps.tumblr.com/ Jay Mantri – free pics under Creative Commons Zero CC0 License http://jaymantri.com/ Free Images – for commercial and personal use under an attribution license http://www.freeimages.co.uk/ The Stocks – Provides the ability to search a number of free image websites http://thestocks.im/ Kaboom Pics – Free images for use anywhere. http://kaboompics.com Fancy Crave – Free under the Creative Commons Zero CC0 License http://fancycrave.com/ Stocka http://www.stocka.co/ Startup Stock Photos http://startupstockphotos.com/ Travel Coffee Book – Listed under Creative Commons CC0 http://travelcoffeebook.com/ DesignersPics http://www.designerspics.com/ Picography http://picography.co/ Barn images http://barnimages.com/ ISO Republic http://isorepublic.com/ Free Range Stock https://freerangestock.com Pixabay - Listed under Creative Commons CC0 https://pixabay.com/ Morgue File http://www.morguefile.com/ Public Domain Archive http://publicdomainarchive.com/ Free Pik http://www.freepik.com/ MMT http://mmt.li/ Free Video Pexels https://videos.pexels.com/ Vimeo https://vimeo.com/creativecommons/cc0 Flickr https://www.flickr.com/search/?q=&l=cc&ct=0&mt=videos&hd=1&adv=1 Videvo http://www.videvo.net/ VideoBlocks – Members Only https://www.videoblocks.com/ More on reddit.com

I want use Peppa pig and wondered how legal is it,

Any character or art created in the last 100 years is copyrighted automatically by the owner unless they specifically and intentionally release it to public domain, which is rare and is never done with corporate owned characters.

Peppa pig is a copyrighted character, you can't use the character at all without permission.

are these images on this site legal at all?

Probably not, looks like the owners of that site are uploading random things they found on the internet that they don't have rights to. There's no way a random site would have the rights to let random people use major corporate characters.

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Public Domain Review: http://publicdomainreview.org/ Pixabay: http://pixabay.com/en/photos/ Digital Comics Museum (status as public domain is not guaranteed, but amazing trove of golden age comic art): http://digitalcomicmuseum.com/ British Library Flickr feed: https://www.flickr.com/photos/britishlibrary/ The Flickr Commons (CC licensed): https://www.flickr.com/commons More on reddit.com