This tiny dinner plate was made c. 1817-33 according to the marks section in Drakard & Holdway's book "Spode Printed Ware". They also show a photo of an entire "Tower" toy dinner service on page 200 of the same book.
This plate is 3" in diameter. It is not perfect. There is crazing, a glaze skip on the back, and a faint hairline crack at the rim. It is marked SPODE printed in blue, and there is also an interesting workman's (or tally) mark.
These early Spode toy plates are seldom found...don't miss it!