I know it's only one day but...
STOCK UP:
1) Mike Thomas
Thomas made the only notable play during the Rams short 7 on 7 period (the day was mainly 11 on 11) when he took a short slant from the left side of the field to the right side of the field, turning the corner, and finding the sideline before being pushed out of bounds for a 30+ yard gain. He doesn't have jets, but he isn't slow. He also made a nice grab in WR drills and looked like a man among boys with the 3s.
2) EJ Gaines
Gaines is arguably the most forgotten man on the Rams D. He showed up to play today covering the slot and outside with no notable completions and came up in run support (albeit w/o pads).
3) Mo Alexander
Has no physical limitations to play free, lets just hope he can progress mentally. There weren't many downfield throws, so I don't want to give the impression he's locked up a starting spot or anything. But he didn't do anything to hurt his case today and filled up nicely in run support, giving Todd a nice pop in the hole coming all the way from his safety position.
STOCK DOWN:
1) Temmarick Hemmingway
As I've said its only day 1, but Hemmingway showed today why he fell in the draft. He is a raw project, who if developed has the physical gifts to be a great TE. That's a big IF however (see Fendi Onobun). He had a ball ripped from his hands by a DB in 7 on 7 and had a CB hit him from behind on a short curl, causing him to drop the ball as well. Hemmingway will need to shine on ST, because he doesn't provide much else currently that the Rams lack at TE.
2) Eric Kush
Had 2 bad snaps to Goff in 11 on 11 in the span of a few plays. The first was a shotgun snap that hit Goff in the feet and the second looked like a bad exchange from under center, however it looked like Kush didn't get the ball all the way to Goff.
Fun Tidbit: I loved how after 11 on 11 (practice was over) Goff was seen taking multiple reps with Kush from both under center and in the shotgun to work on perfecting their exchange.