Mars Yard web site at JPL has some info http://robotics.jpl.nasa.gov/infrastructure/marsyard/homepage.html
That site references a dead link: http://grayskies.atmos.washington.edu/local-httpdocs/mars_data-information/moore_keller_soils.html
http://geology.cr.usgs.gov/pub/open-file-reports/ofr-98-0467/ is an open file report from USGS: Rock-fall Hazards in the Yosemite Valley which has some boulder size distribution information
http://www-k12.atmos.washington.edu/k12/resources/mars_data-information/NASA_TM_4300_1990.html Surface Material Maps of Viking Landing Sites on Mars NASA TM 4300, 1991
JSC-1: A NEW LUNAR SOIL SIMULANT http://www-sn.jsc.nasa.gov/PlanetaryMissions/EXLibrary/DOCS/EIC050.HTML (but it's dead, so I looked at the google cached one..)