So far this is the best one I have found so far It also has a link to donate.
The first global research foundation for endometriosis
The World Endometriosis Research Foundation (WERF™) was created in 2006 as the first global charity to foster research in endometriosis
to improve knowledge and treatments.
WERF's vision is a day when no woman is crippled by endometriosis nor prevented by the disease from having children.
To achieve this vision WERF carries out well powered, international multi-centre trials, and support specific research projects investigating disease mechanisms. WERF is now working with 32 centres in 21 countries.
Research is needed because endometriosis is a big problem!
Having to battle daily debilitating symptoms prevents millions of women to fulfill their dreams of finishing an education, to maintain a career, to have children - and sometimes to maintain relationships. In addition there are significant socio-economic impacts due to the disease.
Hope this helps