Essentially series seed documents were created by a very smart group of bay area attorneys and you can be found those at www.seriesseed.com. essentially series seed is based on standard VC type preferred A stock purchase agreement (as can be found at an nvca.org, the VC organization). However, the series seed documents make the process of issuing preferred stock much easier. instead of having a multiple set of agreements, you only have an investment agreement and an amended certificate of incorporation. in essence the series seed preferred gets same rights as standard preferred A like liquidation preference and anti-dilution however, some rights such as registration rights, which are really not applicable at this stage of the company, are postponed to the future, and basically say that any rights attached to the new preferred A stock will also apply to the series seed preferred stock. So basically, they’re not losing anything. Very effective and should not be expensive.