Parkinson's signing was listed on the official NFL transactions on Tuesday.
Seattle made eight picks in the April draft. Parkinson was taken with the first of Seattle's two fourth-round selections.
At 6-foot-7, Parkinson is another tall target for quarterback Russell Wilson, especially in red-zone situations. Parkinson had 48 receptions and just one drop in his final season at Stanford. He had just one touchdown last season but had seven TD catches in 2018.
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