There are many Native Ad Networks for publishers and websites but the Three best Native Ad Networks that I know of are Outbrain, Taboola and Content.ad
Content.ad is the easiest of the three Native Ad Networks that a publisher can get into since they don't have as strict traffic requirements.
Outbrain and Taboola are better Native Ad Networks with higher CPC but you need a whole lot of website visitors to your website to get approved.
Adsense also has Native Ads that work well on blogs and other websites.