Picked up $800 in $2s and the teller said some were stamped...pretty cool. I have found these before in circulation but many of these are crisp and consecutive, not bad for circ finds.
From the signatures it looks like those are 1976 notes. They are worth a bit over face value... approximately $10-$20 book for an uncirculated note. I personally don't like the stamps... it ruins the bill for me. But I know there are collectors out there who like these "first issue" notes.
I think Clay Irving collects these stamped $2 notes. He may be able to give you a more accurate idea of their value.
They're Series 1976 $2 Federal Reserve Notes with a stamp and a postmark on 13 Apr 1976 (Jefferson's birthday) for the First Day of Issue of the $2 Federal Reserve Note. 1976 was the bicentennial year and some of the notes have an additional postmark on 04 Jul 1976. With the exception of the note with the rusty paper clip impression, they look like they're in an almost uncirculated condition. I look for a few things — The Federal Reserve District, the stamp, the post office location of the postmark, consecutive serial numbers, and unique postmarks. Minneapolis (District I) is the most difficult to find and these notes will sell for the most amount of money. Depending on the other factors above, a Minneapolis District note could be valued between $20 to $50. The 13¢ "13 Star Flag over Independence Hall" stamp (Scott# 1622) is the most common stamp used. The 1¢ "Prominent Americans - Thomas Jefferson" stamp (Scott# 1278) is not very common — Less than 1% of my collection has this stamp. The 10¢ "Jefferson Memorial" stamp (Scott# 1520) is the least common — Only 0.4% of my collection has this stamp. I don't think you'll be able to get $10 to $20 per note for the notes with the "13 Star Flag over Independence Hall" stamp. I'd estimate somewhere in the range of $5 to $10. Bundling consecutive serial numbers may add a little premium. You'll probably be able to get more for the less common stamps. I can't identify the the pinkish-red stamp on the note with serial number D03089100A, but it has a nice postmark indicating "CAPITOL OF" something. It may bring a higher premium than the others. That's about all that I can pull out of the picture provided.