The NFL has officially opened the door for teams to begin negotiations with their own drafted rookies as well as undrafted rookie free agents. The deals won't become official until tomorrow, but essentially all rookies are free to agree to deals with teams.
The Eagles first signing according to several reports is Miami Hurricanes RB Graig Cooper. Cooper was a very highly touted prospect, but as is the case with a curious numbers of Eagles late round/UDFA targets, he tore up his knee late in 2009 which cost him part of last year and clearly limited his effectiveness last year.
He was really looking to be on his way to stardom after a big freshman year where he racked up the 3rd most rushing yards by a true freshman in Miami history (behind Clinton Portis). He does fit the mold of what the Eagles look for, as he's a very good pass catcher as well as runner.
So like they have several times in the past the Eagles are rolling the dice on a guy being undervalued coming off an injury. And really, with 90 roster spots this year, why not?